feat(desktop): mirror call state onto the tray icon (cinny-desktop #4)

Sends `set_tray_call_state` from the same effect as the taskbar thumbbar,
so tray and thumbbar can't disagree. Verified through a real local call:
idle → active → active+muted → active+muted+deafened → active+muted → idle.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/hooks/useTauriThumbbar.ts

@@ -10,7 +10,7 @@ type ThumbbarAction = { action: 'mute' | 'deafen' | 'end' };
  * P5-44 — Taskbar thumbnail toolbar (call controls). While a call is active,
  * mirrors the mic/sound state onto the native `set_thumbbar` command (three
  * Mute / Deafen / End-Call buttons on the Windows taskbar thumbnail toolbar) and
- * hides them when the call ends. Thumb-button clicks come back as the
+ * hides them when the call ends. The tray icon mirrors the same state. Thumb-button clicks come back as the
  * `thumbbar-action` event and drive the real call controls. No-op in the browser.
  */
 export function useTauriThumbbar(): void {
@@ -25,6 +25,9 @@ export function useTauriThumbbar(): void {
 
   useEffect(() => {
     invokeTauri('set_thumbbar', { active, muted, deafened });
+    // [cinny-desktop #4] Same state onto the tray icon + tooltip, from the same
+    // effect so the tray and the thumbbar can never disagree.
+    invokeTauri('set_tray_call_state', { active, muted, deafened });
   }, [active, muted, deafened]);
 
   useTauriEvent<ThumbbarAction>('thumbbar-action', ({ action }) => {