feat(desktop): global Cmd+K palette + UI consistency overhaul

Builds on the clarify/needs-input work with a cross-cutting pass to make
the desktop surfaces feel like one app.

- Global Cmd+K command palette (cmdk): nav, settings deep-links, async
  API-key / MCP-server / archived-session groups, reusable theme sub-page
  (light/dark groups, stays open on pick), loop nav, fuzzy match. Replaces
  per-page settings search.
- Shared SearchField: borderless, underline-on-focus, `field-sizing`
  auto-width. Unifies sessions sidebar, pages, overlays, command center,
  cron; drops bespoke OverlaySearchInput.
- Cron & Profiles converted to OverlayView; flat token-driven panels
  (no card-in-card / divider borders) matching command center.
- `r` refresh hotkey via useRefreshHotkey; drop the visible refresh buttons.
- Button text/textStrong link variants applied across settings & views;
  shared PAGE_INSET_X content gutters.
- Math/ascii loaders replace "Loading…" text placeholders; x-icon close
  over text "Close"; cursor-pointer at the dropdown/select primitive level.

apps/desktop/src/app/chat/composer/index.tsx

@@ -157,6 +157,7 @@ export function ChatBar({
   const showHelpHint = draft === '?'
 
   const gatewayState = useStore($gatewayState)
+
   // When the bar is disabled it's because the gateway isn't open. Distinguish a
   // cold start ("Starting Hermes...") from a dropped connection we're trying to
   // restore (e.g. after the Mac slept) so the stuck state reads as recoverable.
@@ -588,7 +589,9 @@ export function ChatBar({
       return
     }
 
-    if ((event.metaKey || event.ctrlKey) && !event.altKey && !event.shiftKey && event.key.toLowerCase() === 'k') {
+    // Cmd/Ctrl+Shift+K drains the next queued message. Plain Cmd/Ctrl+K is
+    // reserved for the global command palette.
+    if ((event.metaKey || event.ctrlKey) && !event.altKey && event.shiftKey && event.key.toLowerCase() === 'k') {
       event.preventDefault()
 
       if (!busy) {