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/styles.css

@@ -517,6 +517,26 @@
   }
 }
 
+/* Command-palette deep-link: briefly flash the targeted settings row. */
+@keyframes setting-field-flash {
+  0% {
+    background-color: color-mix(in srgb, var(--dt-primary, #f59e0b) 22%, transparent);
+  }
+  100% {
+    background-color: transparent;
+  }
+}
+
+.setting-field-highlight {
+  animation: setting-field-flash 1.6s ease-out;
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .setting-field-highlight {
+    animation: none;
+  }
+}
+
 .arc-border::before {
   content: '';
   position: absolute;