Add per-user ignored audiobooks feature

Introduce a per-user "ignored audiobooks" feature to suppress auto-requests. Changes include:

- Database: add Prisma model IgnoredAudiobook and SQL migration to create ignored_audiobooks table with indexes and FK to users.
- Backend: new API routes to list, add, delete, and check ignored audiobooks (/api/user/ignored-audiobooks, /check/:asin, /:id). Add annotateWithIgnoreStatus utility and integrate it into multiple audiobook list endpoints (popular, new-releases, category, search, authors, series).
- Request creator: add ignore-list check (with sibling-ASIN expansion) and a bypassIgnore option for manual requests; return an 'ignored' reason when blocked.
- Frontend: hooks (useIsIgnored, useToggleIgnore, useIgnoredList) and UI updates — AudiobookCard shows an "Ignored" indicator and AudiobookDetailsModal adds an ignore toggle and propagates local state changes.
- Misc: adjust deduplication duration tolerance (to 5% / min 10 minutes), tweak SWR refresh intervals for shelves/syncing, and small logging/info updates.
- Tests: add unit tests for request-creator ignore logic and update existing tests/mocks to account for ignore annotation; extend prisma test helper with ignoredAudiobook mock.

This commit implements the ignore-list end-to-end (DB, server, client, and tests) so users can ignore specific ASINs and have auto-request flows respect that preference.

prisma/migrations/20260311000000_add_ignored_audiobooks/migration.sql

@@ -0,0 +1,24 @@
+-- CreateTable
+CREATE TABLE "ignored_audiobooks" (
+    "id" TEXT NOT NULL,
+    "user_id" TEXT NOT NULL,
+    "asin" TEXT NOT NULL,
+    "title" TEXT NOT NULL,
+    "author" TEXT NOT NULL,
+    "cover_art_url" TEXT,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "ignored_audiobooks_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "ignored_audiobooks_user_id_idx" ON "ignored_audiobooks"("user_id");
+
+-- CreateIndex
+CREATE INDEX "ignored_audiobooks_asin_idx" ON "ignored_audiobooks"("asin");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "ignored_audiobooks_user_id_asin_key" ON "ignored_audiobooks"("user_id", "asin");
+
+-- AddForeignKey
+ALTER TABLE "ignored_audiobooks" ADD CONSTRAINT "ignored_audiobooks_user_id_fkey" FOREIGN KEY ("user_id") REFERENCES "users"("id") ON DELETE CASCADE ON UPDATE CASCADE;