refactor(sync): replace the session-status setState monkeypatch with an owned API

The global session-status store patched its own setState to derive
active membership for callers replacing statusById — a boundary that
silently trusted any caller passing both fields to keep them consistent.
replaceGlobalSessionStatusById is now the one sanctioned way to swap the
map from outside the event reducers; the runtime-switch reset and the
tests that replaced the map directly go through it, and the patch is
gone. Follow-up to #3126 review.

packages/ui/src/apps/runtimeEndpointReset.ts

@@ -15,7 +15,7 @@ import { useFilesViewTabsStore } from '@/stores/useFilesViewTabsStore';
 import { useTerminalStore } from '@/stores/useTerminalStore';
 import { useSessionUIStore } from '@/sync/session-ui-store';
 import { resetStreamingState } from '@/sync/streaming';
-import { useGlobalSessionStatusStore } from '@/sync/global-session-status';
+import { useGlobalSessionStatusStore, replaceGlobalSessionStatusById } from '@/sync/global-session-status';
 import { resetSessionOrdering } from '@/sync/session-ordering';
 import { resetSessionActivityTiming } from '@/sync/session-activity-timing';
 import { syncDesktopSettings } from '@/lib/persistence';
@@ -57,7 +57,7 @@ export const resetAppForRuntimeEndpointChange = (detail: RuntimeEndpointChangedD
   // 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();
-  useGlobalSessionStatusStore.setState({ statusById: new Map() });
+  replaceGlobalSessionStatusById(new Map());
   resetSessionOrdering();
   // Turn timings belong to the previous instance's sessions, and the reset also
   // restarts the resume window so the switch is treated as a fresh load.