Add release blocklist feature

Introduce a per-request release blocklist to auto-block permanently failing releases and provide admin management. Changes include:

- Database: add BlockedRelease model (blocked_releases) to Prisma schema with unique (requestId, releaseKey) and indexes; documented in backend database docs.
- Service & utils: new blocklist.service, release-key and filter helpers for normalization and matching; processors updated to emit auto-blocks (monitor-download, organize-files, search processors, RSS).
- HTTP API: add admin endpoints GET/DELETE /api/admin/blocklist, DELETE /api/admin/blocklist/[id], and GET /api/admin/blocklist/by-request/[requestId].
- Admin UI: new /admin/blocklist page and numerous React components (toolbar, filters, table, rows, pagination, skeleton, chips, date picker) with URL-driven state hook and per-row unblock UX.
- Tests: add unit/integration tests for service, routes, utils, and updated processor tests.

The blocklist is idempotent (upsert), filters search results before ranking (interactive search shows badges only), and admin-only APIs require auth. This commit wires docs, API, DB, frontend and tests for the new feature.

tests/helpers/prisma.ts

@@ -58,6 +58,7 @@ export const createPrismaMock = () => ({
   userHomeSection: createModelMock(),
   audibleCacheCategory: createModelMock(),
   ignoredAudiobook: createModelMock(),
+  blockedRelease: createModelMock(),
   $queryRaw: vi.fn(),
   $transaction: vi.fn(),
   $disconnect: vi.fn(),