feat(desktop): unified overlay design system, BrandMark & onboarding redesign (#40708)

* fix(desktop): unify dialog/overlay buttons on shared Button component

Replace raw <button> action/text controls across the modal layer (boot
failure, install, update, onboarding, clarify, model-visibility,
notifications, gateway menu) with the shared Button + its variants
(text / ghost / icon-xs). Drops the bespoke square-cornered styling so
every dialog matches the app's slightly-rounded button system, and
swaps clarify-tool's hardcoded "Skip" for the existing i18n string.

* feat(desktop): add dev-only dialog gallery for auditing overlays

A code-split, DEV-gated harness (toggle ⌘/Ctrl+Alt+Shift+D) that triggers
every dialog/overlay so their buttons can be eyeballed in one place:
store-driven overlays (boot failure, updates, notifications, sudo/secret)
plus in-place dialogs (confirm, profile create/rename, attach-url, model
picker/visibility, clarify, tool approval). Never ships to production.

* fix(desktop): use Ctrl+Shift+D for dialog gallery (mac-friendly)

The Cmd/Ctrl+Alt+Shift+D chord is impractical on macOS (Option mangles
the keypress). Ctrl+Shift+D is the same chord on every platform and uses
neither Cmd nor Option.

* fix(desktop): stop overriding button icon size to size-4

Action buttons hardcoded size-4 icons, overriding the Button component's
built-in size-3.5. That extra 2px is why boot-failure / onboarding / gateway
buttons looked chunkier than the settings "Apply" (size-3.5 spinner) despite
being the same component+size. Drop the overrides so icons inherit 3.5.

* feat(desktop): add BrandMark, use it in the updates overlay hero

New BrandMark renders the white logo.png on a hardcoded brand-blue tile
(#0000F2 light / #222 dark), replacing the generic Sparkles hero glyph in
the "update available" overlay. Trying it here first to iterate on the look.

NOTE: apps/desktop/public/logo.png is currently a 1x1 placeholder — the tile
renders now; the glyph appears once the real white logo art is dropped in.

* feat(desktop): add real logo.png asset, render it white in BrandMark

logo.png is blue line-art on transparent, so force it white via filter to
read on both the brand-blue (#0000F2) and near-black (#222) tiles. Bump the
glyph to 62% of the tile for the portrait aspect.

* fix(desktop): BrandMark renders logo as-is, no light bg/radius/padding

Drop the white filter, the hardcoded light-mode blue tile, the radius, and
the inner padding. Logo now fills the tile over a transparent surface in
light mode; dark keeps the #222 tile.

* fix(desktop): bump updates-overlay BrandMark to size-16

* feat(desktop): use downscaled karb.webp in BrandMark

Swap the BrandMark glyph to karb.webp, downscaled from 1129x1418/888KB to
254x320/81KB for the hero badge.

* feat(desktop): use nous-girl mark in BrandMark, invert in dark

Key the white background to transparent so only the black line-art remains
(384px/20KB webp). Light mode shows black art; dark mode flips it white via
dark:invert on the #222 tile. Drop the now-unused karb.webp and logo.png.

* fix(desktop): BrandMark uses nous-girl as-is (no transparent/invert)

The dark-mode invert read as a creepy negative. Use the opaque black-on-white
mark unchanged in both themes; drop the white-key, dark:invert, and #222 tile.

* fix(desktop): give BrandMark an explicit white bg tile

* fix(desktop): use nous-girl.jpg directly in BrandMark

* perf(desktop): downscale nous-girl.jpg to 256x256 (466KB -> 19KB)

* style(desktop): bump nous light --theme-secondary to 14% blue

* fix(desktop): outline button is transparent, not chrome-filled

The outline variant used bg-background (the chrome color), so on cards/overlays
with a different surface it rendered as an odd gray-blue fill (visible on the
boot overlay's Repair install / Use local gateway). Make it bg-transparent so
it inherits the surface like a real outline. Reverts the unrelated
--theme-secondary tweak.

* fix(desktop): clean outline button — thin border, no shadow/fill

Drop shadow-xs and the resting fills (light chrome bg, dark bg-input/30) so
outline is just a thin clean border with a subtle hover, in both themes.

* fix(desktop): stop forcing tertiary bg on outline buttons

A global [data-variant='outline'] rule set background: var(--ui-bg-tertiary),
which (attribute-selector specificity) overrode the cva bg-transparent — so
outline buttons always showed the pale tertiary fill on cards/overlays
regardless of the variant classes. Scope that fill to secondary only; outline
is now a true transparent border.

* style(desktop): unified overlay design system + restore #38631 flat-UI

Overlays/dialogs/toasts share a custom shadow-nous (downward-weighted) and
--stroke-nous hairline instead of hard borders: boot-failure, install,
notifications, model-picker, onboarding, prompt-overlays, updates, Dialog.

- button: outline is a 1px inset ring (no fill/shadow); chrome lives in Button
- BrandMark: 256px nous-girl mark replaces sparkle glyphs (updates/onboarding/about)
- onboarding: conditional header, lemniscate-bloom loaders, OTP device-code boxes,
  NOUS CONNECTED hero (ascii decode) + cuneiform easter egg, "Begin" matrix exit
- shared LogView + ErrorState; math/ascii loaders over "Loading..." text
- appearance-settings flattened to SegmentedControl/ListRow; keybind-panel on
  shadow-nous + text-variant reset
- restore flat-UI clobbered by #38631's stale-squash (4a1907bd1): command-center,
  profiles, skills, messaging, cron de-boxed; shared SearchField + PAGE_INSET_X;
  profiles back on OverlaySplitLayout; skills tabs+search one row, no row dividers

* refactor(desktop): clean pass — drop dead code, dedupe, fix stale docs

- log-view: drop unused `bare` prop + forwardRef (no caller uses ref)
- install-overlay: drop `stateOverride` (only the removed dev gallery used it)
- profiles: ProfilesViewProps down to { onClose } (drop vestigial section/titlebar)
- onboarding: hoist shared PROVIDER_ROW_CLASS (was duplicated 2x)
- brand-mark / error-state: tighten comments, fix stale AlertCircle reference

apps/desktop/src/app/skills/index.tsx

@@ -15,6 +15,7 @@ import type { SkillInfo, ToolsetInfo } from '@/types/hermes'
 
 import { useRefreshHotkey } from '../hooks/use-refresh-hotkey'
 import { useRouteEnumParam } from '../hooks/use-route-enum-param'
+import { PAGE_INSET_X } from '../layout-constants'
 import { PageSearchShell } from '../page-search-shell'
 import { asText, includesQuery, prettyName, toolNames, toolsetDisplayLabel } from '../settings/helpers'
 import { ToolsetConfigPanel } from '../settings/toolset-config-panel'
@@ -191,32 +192,22 @@ export function SkillsView({ setStatusbarItemGroup: _setStatusbarItemGroup, ...p
     <PageSearchShell
       {...props}
       filters={
-        <>
-          <div className="flex flex-wrap items-center justify-center gap-x-2 gap-y-1">
-            <TextTab active={mode === 'skills'} onClick={() => setMode('skills')}>
-              {t.skills.tabSkills}
+        mode === 'skills' && categories.length > 0 ? (
+          <>
+            <TextTab active={activeCategory === null} onClick={() => setActiveCategory(null)}>
+              {t.skills.all} <TextTabMeta>{totalSkills}</TextTabMeta>
             </TextTab>
-            <TextTab active={mode === 'toolsets'} onClick={() => setMode('toolsets')}>
-              {t.skills.tabToolsets}
-            </TextTab>
-          </div>
-          {mode === 'skills' && categories.length > 0 && (
-            <div className="flex flex-wrap justify-center gap-x-2 gap-y-1">
-              <TextTab active={activeCategory === null} onClick={() => setActiveCategory(null)}>
-                {t.skills.all} <TextTabMeta>{totalSkills}</TextTabMeta>
+            {categories.map(category => (
+              <TextTab
+                active={activeCategory === category.key}
+                key={category.key}
+                onClick={() => setActiveCategory(activeCategory === category.key ? null : category.key)}
+              >
+                {prettyName(category.key)} <TextTabMeta>{category.count}</TextTabMeta>
               </TextTab>
-              {categories.map(category => (
-                <TextTab
-                  active={activeCategory === category.key}
-                  key={category.key}
-                  onClick={() => setActiveCategory(activeCategory === category.key ? null : category.key)}
-                >
-                  {prettyName(category.key)} <TextTabMeta>{category.count}</TextTabMeta>
-                </TextTab>
-              ))}
-            </div>
-          )}
-        </>
+            ))}
+          </>
+        ) : undefined
       }
       onSearchChange={setQuery}
       searchHidden={mode === 'skills' ? (skills?.length ?? 0) === 0 : (toolsets?.length ?? 0) === 0}
@@ -236,21 +227,33 @@ export function SkillsView({ setStatusbarItemGroup: _setStatusbarItemGroup, ...p
         </Button>
       }
       searchValue={query}
+      tabs={
+        <>
+          <TextTab active={mode === 'skills'} onClick={() => setMode('skills')}>
+            {t.skills.tabSkills}
+          </TextTab>
+          <TextTab active={mode === 'toolsets'} onClick={() => setMode('toolsets')}>
+            {t.skills.tabToolsets}
+          </TextTab>
+        </>
+      }
     >
       {!skills || !toolsets ? (
         <PageLoader label={t.skills.loading} />
       ) : mode === 'skills' ? (
-        <div className="h-full overflow-y-auto px-4 py-3">
+        <div className={cn('h-full overflow-y-auto py-3', PAGE_INSET_X)}>
           {visibleSkills.length === 0 ? (
             <EmptyState description={t.skills.noSkillsDesc} title={t.skills.noSkillsTitle} />
           ) : (
             <div className="space-y-4">
               {skillGroups.map(([category, list]) => (
                 <div className="space-y-1.5" key={category}>
-                  <div className="text-[0.68rem] font-semibold uppercase tracking-[0.12em] text-muted-foreground">
-                    {prettyName(category)}
-                  </div>
-                  <div className="divide-y divide-(--ui-stroke-quaternary)">
+                  {activeCategory === null && (
+                    <div className="text-[0.68rem] font-semibold uppercase tracking-[0.12em] text-muted-foreground">
+                      {prettyName(category)}
+                    </div>
+                  )}
+                  <div>
                     {list.map(skill => (
                       <div
                         className="grid gap-3 px-0 py-2.5 sm:grid-cols-[minmax(0,1fr)_auto] sm:items-center"
@@ -276,7 +279,7 @@ export function SkillsView({ setStatusbarItemGroup: _setStatusbarItemGroup, ...p
           )}
         </div>
       ) : (
-        <div className="h-full overflow-y-auto px-4 py-3">
+        <div className={cn('h-full overflow-y-auto py-3', PAGE_INSET_X)}>
           {visibleToolsets.length === 0 ? (
             <EmptyState description={t.skills.noToolsetsDesc} title={t.skills.noToolsetsTitle} />
           ) : (
@@ -284,7 +287,7 @@ export function SkillsView({ setStatusbarItemGroup: _setStatusbarItemGroup, ...p
               <div className="text-xs text-muted-foreground">
                 {t.skills.toolsetsEnabled(enabledToolsets, toolsets.length)}
               </div>
-              <div className="divide-y divide-(--ui-stroke-quaternary)">
+              <div>
                 {visibleToolsets.map(toolset => {
                   const tools = toolNames(toolset)
                   const label = toolsetDisplayLabel(toolset)