Keep workspace focus mode scoped and easy to exit (#2151)

* fix(workspace): keep focus mode scoped and easy to exit

Route focus mode through the active workspace so persisted state cannot hide chrome on settings or other screens. Add a visible exit control and keep desktop window chrome aligned and visually quiet.

* fix(app): clarify muted chrome semantics

packages/app/src/hooks/use-keyboard-shortcuts.ts

@@ -34,14 +34,12 @@ export function useKeyboardShortcuts({
   isMobile,
   toggleAgentList,
   toggleBothSidebars,
-  toggleFocusMode,
   cycleTheme,
 }: {
   enabled: boolean;
   isMobile: boolean;
   toggleAgentList: () => void;
   toggleBothSidebars?: () => void;
-  toggleFocusMode?: () => void;
   cycleTheme?: () => void;
 }) {
   const pathname = usePathname();
@@ -105,7 +103,6 @@ export function useKeyboardShortcuts({
     const callbacksByName: Record<ShortcutCallbackName, (() => void) | undefined> = {
       "toggle-agent-list": toggleAgentList,
       "toggle-both-sidebars": toggleBothSidebars,
-      "toggle-focus-mode": toggleFocusMode,
       "cycle-theme": cycleTheme,
     };
 
@@ -305,6 +302,5 @@ export function useKeyboardShortcuts({
     router,
     toggleAgentList,
     toggleBothSidebars,
-    toggleFocusMode,
   ]);
 }