feat(web): notification settings per kind and channel (#5345, web half)

- A Notifications section on Settings has a row per kind and a toggle
  each for Inbox, Phone and Email. Labels are short, menu-style.
- Admin kinds sit under "Library health", for admins only.
- Toggles are optimistic and send only the kind and channel touched. A
  failed save reverts unless something newer has happened (snippet
  #5106's generation counter).
- With the inbox off, phone and email are disabled: they ride on it.
- When email isn't usable, one line says why. With no address it links
  to the profile. With no SMTP an admin gets a link to Integrations and a
  listener is simply told. Saving the profile refreshes the settings so
  the line clears.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/lib/components/Shell.test.ts

@@ -26,10 +26,6 @@ vi.mock('$lib/auth/store.svelte', () => ({
 
 // The bell's queries need a QueryClient the Shell tests do not provide; its own
 // behaviour is covered in NotificationBell.test.ts.
-vi.mock('@tanstack/svelte-query', async (orig) => {
-  const actual = (await orig()) as Record<string, unknown>;
-  return { ...actual, useQueryClient: () => ({ invalidateQueries: vi.fn() }) };
-});
 vi.mock('$lib/api/notifications', async () => {
   const { mockQuery } = await import('../../test-utils/query');
   return {