feat: migration DB — table series avec UUID PK (fusionne series_metadata)

Migration 0070:
- Crée table series (id UUID PK, library_id FK, name, description, authors,
  publishers, status, locked_fields, original_name, etc.)
- Peuple depuis books + series_metadata existants
- Ajoute series_id FK à: books, external_metadata_links, anilist_series_links,
  available_downloads, download_detection_results
- Backfill tous les series_id par matching nom

Migration 0071:
- Supprime les colonnes TEXT legacy (books.series, *.series_name)
- Drop table series_metadata (fusionnée dans series)
- Recrée les contraintes UNIQUE sur series_id au lieu de series_name
- Nettoie les rows orphelines (series_id NULL)
- Ajoute index sur series_id dans toutes les tables

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

infra/migrations/0070_create_series_table.sql

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+-- =============================================================================
+-- Migration 0070: Create proper `series` table with UUID PK
+-- Fuses series_metadata into series. All related tables get series_id FK.
+-- =============================================================================
+
+-- 1. Create the series table (fusion of series_metadata)
+CREATE TABLE IF NOT EXISTS series (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    library_id UUID NOT NULL REFERENCES libraries(id) ON DELETE CASCADE,
+    name TEXT NOT NULL,
+    description TEXT,
+    authors TEXT[] NOT NULL DEFAULT '{}',
+    publishers TEXT[] NOT NULL DEFAULT '{}',
+    start_year INTEGER,
+    total_volumes INTEGER,
+    status TEXT,
+    locked_fields JSONB NOT NULL DEFAULT '{}',
+    original_name TEXT,
+    book_author TEXT,
+    book_language TEXT,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (library_id, name)
+);
+
+CREATE INDEX IF NOT EXISTS idx_series_library_id ON series(library_id);
+
+-- 2. Populate from existing data
+
+-- From books (all series with at least one book)
+INSERT INTO series (library_id, name)
+SELECT DISTINCT b.library_id, COALESCE(NULLIF(b.series, ''), 'unclassified')
+FROM books b
+ON CONFLICT (library_id, name) DO NOTHING;
+
+-- From series_metadata (series with metadata but possibly no books)
+INSERT INTO series (library_id, name)
+SELECT sm.library_id, sm.name FROM series_metadata sm
+ON CONFLICT (library_id, name) DO NOTHING;
+
+-- Merge series_metadata columns into series
+UPDATE series s SET
+    description = sm.description,
+    authors = sm.authors,
+    publishers = sm.publishers,
+    start_year = sm.start_year,
+    total_volumes = sm.total_volumes,
+    status = sm.status,
+    locked_fields = sm.locked_fields,
+    original_name = sm.original_name,
+    created_at = sm.created_at,
+    updated_at = sm.updated_at
+FROM series_metadata sm
+WHERE sm.library_id = s.library_id AND sm.name = s.name;
+
+-- 3. Add series_id FK to books
+ALTER TABLE books ADD COLUMN IF NOT EXISTS series_id UUID REFERENCES series(id) ON DELETE SET NULL;
+UPDATE books b SET series_id = s.id
+FROM series s
+WHERE s.library_id = b.library_id
+  AND s.name = COALESCE(NULLIF(b.series, ''), 'unclassified')
+  AND b.series_id IS NULL;
+CREATE INDEX IF NOT EXISTS idx_books_series_id ON books(series_id);
+
+-- 4. Add series_id FK to external_metadata_links
+ALTER TABLE external_metadata_links ADD COLUMN IF NOT EXISTS series_id UUID REFERENCES series(id) ON DELETE CASCADE;
+UPDATE external_metadata_links eml SET series_id = s.id
+FROM series s
+WHERE s.library_id = eml.library_id AND LOWER(s.name) = LOWER(eml.series_name)
+  AND eml.series_id IS NULL;
+
+-- 5. Add series_id FK to anilist_series_links
+ALTER TABLE anilist_series_links ADD COLUMN IF NOT EXISTS series_id UUID REFERENCES series(id) ON DELETE CASCADE;
+UPDATE anilist_series_links asl SET series_id = s.id
+FROM series s
+WHERE s.library_id = asl.library_id AND LOWER(s.name) = LOWER(asl.series_name)
+  AND asl.series_id IS NULL;
+
+-- 6. Add series_id FK to available_downloads
+ALTER TABLE available_downloads ADD COLUMN IF NOT EXISTS series_id UUID REFERENCES series(id) ON DELETE CASCADE;
+UPDATE available_downloads ad SET series_id = s.id
+FROM series s
+WHERE s.library_id = ad.library_id AND LOWER(s.name) = LOWER(ad.series_name)
+  AND ad.series_id IS NULL;
+
+-- 7. Add series_id FK to download_detection_results
+ALTER TABLE download_detection_results ADD COLUMN IF NOT EXISTS series_id UUID REFERENCES series(id) ON DELETE CASCADE;
+UPDATE download_detection_results ddr SET series_id = s.id
+FROM series s
+WHERE s.library_id = ddr.library_id AND LOWER(s.name) = LOWER(ddr.series_name)
+  AND ddr.series_id IS NULL;
+
+-- NOTE: Old TEXT columns (books.series, *.series_name) are kept for now.
+-- They will be dropped in a future migration (0071) once all code is migrated.

infra/migrations/0071_drop_series_legacy_columns.sql

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+-- =============================================================================
+-- Migration 0071: Drop legacy TEXT columns now replaced by series_id FK
+-- Prerequisite: migration 0070 must have run and all code must use series_id
+-- =============================================================================
+
+-- 1. Drop old TEXT series column from books (replaced by series_id FK)
+ALTER TABLE books DROP COLUMN IF EXISTS series;
+
+-- 2. Drop old TEXT series_name columns from related tables
+ALTER TABLE external_metadata_links DROP COLUMN IF EXISTS series_name;
+ALTER TABLE anilist_series_links DROP COLUMN IF EXISTS series_name;
+ALTER TABLE available_downloads DROP COLUMN IF EXISTS series_name;
+ALTER TABLE download_detection_results DROP COLUMN IF EXISTS series_name;
+
+-- 3. Drop the old series_metadata table (fused into series)
+DROP TABLE IF EXISTS series_metadata;
+
+-- 4. Drop old composite indexes that relied on series_name text matching
+DROP INDEX IF EXISTS idx_eml_library_series;
+
+-- 5. Add missing indexes on series_id columns
+CREATE INDEX IF NOT EXISTS idx_eml_series_id ON external_metadata_links(series_id);
+CREATE INDEX IF NOT EXISTS idx_asl_series_id ON anilist_series_links(series_id);
+CREATE INDEX IF NOT EXISTS idx_ad_series_id ON available_downloads(series_id);
+CREATE INDEX IF NOT EXISTS idx_ddr_series_id ON download_detection_results(series_id);
+
+-- 6. Update unique constraints to use series_id instead of series_name
+-- external_metadata_links: (library_id, series_name, provider) → (series_id, provider)
+ALTER TABLE external_metadata_links DROP CONSTRAINT IF EXISTS external_metadata_links_library_id_series_name_provider_key;
+DO $$ BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM pg_constraint WHERE conname = 'external_metadata_links_series_id_provider_key'
+    ) THEN
+        ALTER TABLE external_metadata_links
+            ADD CONSTRAINT external_metadata_links_series_id_provider_key UNIQUE (series_id, provider);
+    END IF;
+END $$;
+
+-- anilist_series_links: old PK was (library_id, series_name, provider)
+-- Need to recreate with series_id. First drop old PK, add id column, create new PK.
+DO $$ BEGIN
+    -- Add id column if not exists
+    IF NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_name = 'anilist_series_links' AND column_name = 'id'
+    ) THEN
+        ALTER TABLE anilist_series_links ADD COLUMN id UUID DEFAULT gen_random_uuid();
+        -- Drop old composite PK
+        ALTER TABLE anilist_series_links DROP CONSTRAINT IF EXISTS anilist_series_links_pkey;
+        -- Set new PK
+        ALTER TABLE anilist_series_links ADD PRIMARY KEY (id);
+        -- Add unique on (series_id, provider)
+        ALTER TABLE anilist_series_links
+            ADD CONSTRAINT anilist_series_links_series_id_provider_key UNIQUE (series_id, provider);
+    END IF;
+END $$;
+
+-- available_downloads: old unique was (library_id, series_name)
+ALTER TABLE available_downloads DROP CONSTRAINT IF EXISTS available_downloads_library_id_series_name_key;
+DO $$ BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM pg_constraint WHERE conname = 'available_downloads_series_id_key'
+    ) THEN
+        ALTER TABLE available_downloads
+            ADD CONSTRAINT available_downloads_series_id_key UNIQUE (series_id);
+    END IF;
+END $$;
+
+-- 7. Clean up orphaned rows (series_id IS NULL after migration 0070)
+DELETE FROM external_metadata_links WHERE series_id IS NULL;
+DELETE FROM anilist_series_links WHERE series_id IS NULL;
+DELETE FROM available_downloads WHERE series_id IS NULL;
+DELETE FROM download_detection_results WHERE series_id IS NULL;
+
+-- 8. Make series_id NOT NULL now that all data is migrated
+ALTER TABLE external_metadata_links ALTER COLUMN series_id SET NOT NULL;
+ALTER TABLE anilist_series_links ALTER COLUMN series_id SET NOT NULL;
+ALTER TABLE available_downloads ALTER COLUMN series_id SET NOT NULL;
+-- download_detection_results keeps series_id nullable (temp job data)
+
+-- 9. Drop library_id from tables where it's now redundant (available via series.library_id JOIN)
+-- Keep library_id for now on anilist_series_links and external_metadata_links for query convenience
+-- Only drop from available_downloads and download_detection_results where it's truly redundant
+-- Actually, keep all library_id columns for query performance (avoids extra JOIN)