Add per-user home sections & unified Audible cache

Introduce per-user configurable home page sections and a unified Audible cache/category model. Adds Prisma models (UserHomeSection, AudibleCacheCategory) and migrations to create tables and remove legacy popular/new_release flags; updates schema.prisma accordingly. Add API routes for user home sections, live Audible categories, and category-based audiobook listing, and refactor popular/new-releases/covers routes to read from AudibleCacheCategory. Frontend: new HomeSection component, HomeSectionConfigModal, useHomeSections hook, and homepage changes to render dynamic sections plus image fallback to a placeholder SVG. Also add placeholder_cover.svg and tests for home sections and the audible refresh processor.

prisma/migrations/20260306000000_add_home_sections/migration.sql

@@ -0,0 +1,49 @@
+-- CreateTable
+CREATE TABLE "user_home_sections" (
+    "id" TEXT NOT NULL,
+    "user_id" TEXT NOT NULL,
+    "section_type" TEXT NOT NULL,
+    "category_id" TEXT,
+    "category_name" TEXT,
+    "sort_order" INTEGER NOT NULL,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "user_home_sections_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "audible_cache_categories" (
+    "id" TEXT NOT NULL,
+    "asin" TEXT NOT NULL,
+    "category_id" TEXT NOT NULL,
+    "rank" INTEGER NOT NULL,
+    "last_synced_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "audible_cache_categories_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "user_home_sections_user_id_idx" ON "user_home_sections"("user_id");
+
+-- CreateIndex
+CREATE INDEX "user_home_sections_sort_order_idx" ON "user_home_sections"("sort_order");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "user_home_sections_user_id_section_type_category_id_key" ON "user_home_sections"("user_id", "section_type", "category_id");
+
+-- CreateIndex
+CREATE INDEX "audible_cache_categories_category_id_idx" ON "audible_cache_categories"("category_id");
+
+-- CreateIndex
+CREATE INDEX "audible_cache_categories_asin_idx" ON "audible_cache_categories"("asin");
+
+-- CreateIndex
+CREATE INDEX "audible_cache_categories_category_id_rank_idx" ON "audible_cache_categories"("category_id", "rank");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "audible_cache_categories_asin_category_id_key" ON "audible_cache_categories"("asin", "category_id");
+
+-- AddForeignKey
+ALTER TABLE "user_home_sections" ADD CONSTRAINT "user_home_sections_user_id_fkey" FOREIGN KEY ("user_id") REFERENCES "users"("id") ON DELETE CASCADE ON UPDATE CASCADE;

prisma/migrations/20260307000000_remove_popular_newrelease_flags/migration.sql

@@ -0,0 +1,17 @@
+-- DropIndex
+DROP INDEX IF EXISTS "audible_cache_is_popular_idx";
+
+-- DropIndex
+DROP INDEX IF EXISTS "audible_cache_is_new_release_idx";
+
+-- DropIndex
+DROP INDEX IF EXISTS "audible_cache_popular_rank_idx";
+
+-- DropIndex
+DROP INDEX IF EXISTS "audible_cache_new_release_rank_idx";
+
+-- AlterTable - Remove legacy discovery flag columns (now stored in audible_cache_categories)
+ALTER TABLE "audible_cache" DROP COLUMN "is_popular",
+DROP COLUMN "is_new_release",
+DROP COLUMN "popular_rank",
+DROP COLUMN "new_release_rank";