fix(02): wire calendar-controls plugin and Zustand selectors

Bug A — navigation no-op: replace $app.calendarState private-API poking
with the official @schedule-x/calendar-controls plugin. CalendarShell
creates the plugin once via useState stable initialiser and passes it to
ViewToolbar as `controls`. ViewToolbar calls controls.setDate(PlainDate)
and controls.setView(id) for all navigation and view-switching. Step size
matches the active view: day→±1 day, week→±1 week, month-*→±1 month.

Bug B — popover-open calendar flash: replace the unselected
useCalendarStore() destructuring in CalendarShell and ViewToolbar with
per-field selectors. Neither component now subscribes to openEventId, so
popover open/close no longer triggers a re-render that rebuilds the
Schedule-X config.

- Add @schedule-x/calendar-controls@4.6.0 dependency
- Update CalendarShell.test.tsx: add vi.mock for calendar-controls
- typecheck, vitest (37/37), build all pass

apps/pwa/src/components/CalendarShell.test.tsx

@@ -56,6 +56,41 @@ vi.mock('@schedule-x/event-modal', () => ({
   })),
 }))
 
+// Mock @schedule-x/calendar-controls so CalendarShell can create the plugin
+vi.mock('@schedule-x/calendar-controls', () => ({
+  createCalendarControlsPlugin: vi.fn(() => ({
+    name: 'calendarControls',
+    beforeRender: vi.fn(),
+    onRender: vi.fn(),
+    setDate: vi.fn(),
+    setView: vi.fn(),
+    getDate: vi.fn(() => Temporal.Now.plainDateISO()),
+    getView: vi.fn(() => 'month-grid'),
+    setFirstDayOfWeek: vi.fn(),
+    setLocale: vi.fn(),
+    setViews: vi.fn(),
+    setDayBoundaries: vi.fn(),
+    setWeekOptions: vi.fn(),
+    setCalendars: vi.fn(),
+    setMinDate: vi.fn(),
+    setMaxDate: vi.fn(),
+    setMonthGridOptions: vi.fn(),
+    setTimezone: vi.fn(),
+    setResources: vi.fn(),
+    getFirstDayOfWeek: vi.fn(),
+    getLocale: vi.fn(),
+    getViews: vi.fn(() => []),
+    getDayBoundaries: vi.fn(),
+    getWeekOptions: vi.fn(),
+    getCalendars: vi.fn(() => ({})),
+    getMinDate: vi.fn(),
+    getMaxDate: vi.fn(),
+    getMonthGridOptions: vi.fn(),
+    getResources: vi.fn(() => []),
+    getRange: vi.fn(() => null),
+  })),
+}))
+
 // Mock the API client
 vi.mock('../api/client.js', () => ({
   fetchMe: vi.fn(),