feat(mobile): synchronized pill composer transitions and draft screen fixes

Drop the animated pill/composer morph in favor of instant swaps that are
synchronized with the keyboard choreography: a new oc:keyboard-intent
event collapses the composer (flushSync) before the hide compensation is
measured, so keyboard travel and composer height change land as a single
chat motion on both iOS and Android (Android also gains keyboard signals
and deterministic re-pins around its native resize). The WKWebView caret
is hidden during the transition so it no longer flies to its new position.

Draft screen: starter chips hide instantly while the keyboard is up and
the centered title rides the keyboard shift compensation instead of
double-jumping; the composer drag handle also works in dictation mode;
the highlight mirror is disabled on mobile so the caret matches the text.

Fixes: worktree discovery and the GitHub auth probe now wait for the
runtime connection (no more empty branch pickers / stale auth on cold
start), worktree discovery merges per project instead of clobbering the
persisted map, the cross-project session list resets on instance switch
(with an in-flight load guard) so no stale sessions linger, and mobile
overlay content contains its overscroll instead of bouncing the page.

packages/ui/src/apps/runtimeEndpointReset.ts

@@ -3,6 +3,7 @@ import type { RuntimeEndpointChangedDetail } from '@/lib/runtime-switch';
 import { disposeTerminalInputTransport } from '@/lib/terminalApi';
 import { useConfigStore } from '@/stores/useConfigStore';
 import { useProjectsStore } from '@/stores/useProjectsStore';
+import { useGlobalSessionsStore } from '@/stores/useGlobalSessionsStore';
 import { useAutoReviewStore } from '@/stores/useAutoReviewStore';
 import { useUIStore } from '@/stores/useUIStore';
 import { useSessionUIStore } from '@/sync/session-ui-store';
@@ -25,6 +26,9 @@ export const resetAppForRuntimeEndpointChange = (detail: RuntimeEndpointChangedD
     lastDisconnectReason: null,
   });
   useProjectsStore.getState().resetForRuntimeSwitch();
+  // Cross-project session list (mobile sessions sheet & co) belongs to the
+  // previous instance — drop it so stale sessions can't linger after a switch.
+  useGlobalSessionsStore.getState().resetForRuntimeSwitch();
   useSessionUIStore.getState().restoreForRuntimeSwitch(detail.runtimeKey);
   useUIStore.getState().restoreForRuntimeSwitch(detail.runtimeKey);
   resetStreamingState();