feat(library): replace/upgrade an owned album on demand

Add Request.force (migration add_request_force): the pipeline's intake now
skips the "already in library" dedupe for a forced job, so an owned album is
re-downloaded. The import step still keeps the new copy only when it's higher
quality, so a forced upgrade can never downgrade what's on disk.

- Worker: _is_force_job → dedupe bypassed when Request.force.
- POST /api/library/[id]/upgrade finds the matching MonitoredRelease and
  enqueues a force request (guards against stacking on an in-flight job).
- Library route exposes monitoredReleaseId; the album modal shows a
  "Replace / upgrade" button when a release exists.

Worker + web tests added (pipeline force re-acquire; upgrade route).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/prisma/migrations/20260714192517_add_request_force/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "Request" ADD COLUMN     "force" BOOLEAN NOT NULL DEFAULT false;

web/prisma/schema.prisma

@@ -35,6 +35,10 @@ model Request {
   album       String
   status      RequestStatus @default(pending)
   createdAt   DateTime      @default(now())
+  // Force re-acquisition: skip the "already in library" dedupe so an owned album is
+  // re-downloaded on demand. The import step still keeps the copy only if it's higher
+  // quality, so a forced upgrade never downgrades. Set by the Library "Replace / upgrade".
+  force       Boolean       @default(false)
   job         Job?
   libraryItem LibraryItem?