chore(deps): SvelteKit 3 with adapter-static 4 and TypeScript 6, full-tree npm audit (#5021)

Merges Renovate's kit 3 (PR #149) and adapter-static 4 (PR #148) bumps,
plus the migration they need. The mechanical part is `sv migrate
sveltekit-3`, run one task at a time and reviewed:

- svelte.config.js is gone. Its options move into sveltekit() in
  vite.config.ts, exported as kitOptions so vitest.config.ts runs the
  same kit setup, including the $test-utils alias the tests import.
- $lib becomes #lib through package.json "imports". There is no
  src/lib/index, so only the "#lib/*" entry is kept.
- tsconfig extends $app/tsconfig.
- Peer floors raised to kit 3's requirements: svelte ^5.57.1, vite
  ^8.0.12, svelte-check ^4.7.5.

By hand, from the codemod's list of non-automated tasks:

- goto's replaceState option is now replace; keepFocus becomes
  reset: false. For the search typeahead, reset: false also stops the
  scroll-to-top, which is wanted while typing.
- The test setup mocks drop pushState/replaceState and $app/paths
  base/assets, which kit 3 removed, and mock refreshAll in place of
  invalidateAll.
- The other flagged files only read page.url or goto internal routes,
  so they needed no change.

TypeScript goes to ^6, not the ^7 Renovate offers: kit 3 declares
typescript ^6 as a peer and svelte-check 4.7 accepts ^5 || ^6. Move to
7 once both accept it.

With Tailwind 4 and kit 3 in, `npm audit` on the whole tree reports 0,
so the web lane now audits every dependency rather than only what
ships to browsers.

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

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

@@ -43,11 +43,11 @@ const playlistsData = vi.hoisted(() => ({
   public: [] as unknown[]
 }));
 
-vi.mock('$lib/auth/store.svelte', () => ({
+vi.mock('#lib/auth/store.svelte.js', () => ({
   user: { value: { id: 'u-self', username: 'me', is_admin: false } }
 }));
 
-vi.mock('$lib/api/playlists', () => ({
+vi.mock('#lib/api/playlists.js', () => ({
   createPlaylistsQuery: () =>
     readable({ data: playlistsData, isPending: false, isError: false }),
   appendTracks: vi.fn().mockResolvedValue({ id: 'p1', tracks: [] }),
@@ -86,7 +86,7 @@ describe('AddToPlaylistMenu', () => {
 
   test('clicking a playlist appends and closes', async () => {
     const onClose = vi.fn();
-    const { appendTracks } = await import('$lib/api/playlists');
+    const { appendTracks } = await import('#lib/api/playlists.js');
     render(AddToPlaylistMenu, { props: { tracks: [track], onClose } });
     await fireEvent.click(screen.getByRole('menuitem', { name: /A-list/ }));
     await waitFor(() => expect(onClose).toHaveBeenCalled());