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/routes/admin/missing-files/+page.svelte

@@ -1,11 +1,11 @@
 <script lang="ts">
-  import { pageTitle } from '$lib/branding';
+  import { pageTitle } from '#lib/branding.js';
   import { FolderX, Music2 } from 'lucide-svelte';
-  import { createMissingFilesQuery } from '$lib/api/admin';
-  import { relativeTime, timeUntil } from '$lib/utils/relativeTime';
-  import { coverUrl } from '$lib/media/covers';
-  import ReacquisitionSettingsCard from '$lib/components/ReacquisitionSettingsCard.svelte';
-  import type { AdminMissingGroup } from '$lib/api/types';
+  import { createMissingFilesQuery } from '#lib/api/admin.js';
+  import { relativeTime, timeUntil } from '#lib/utils/relativeTime.js';
+  import { coverUrl } from '#lib/media/covers.js';
+  import ReacquisitionSettingsCard from '#lib/components/ReacquisitionSettingsCard.svelte';
+  import type { AdminMissingGroup } from '#lib/api/types.js';
 
   // Files the scan looked for and could not find. Read-only on purpose:
   // a missing file keeps its track row, its play history and its likes,