feat: add batch metadata jobs, series filters, and translate backoffice to French

- Add metadata_batch job type with background processing via tokio::spawn
- Auto-apply metadata only when single result at 100% confidence
- Support primary + fallback provider per library, "none" to opt out
- Add batch report/results API endpoints and job detail UI
- Add series_status and has_missing filters to both series listing pages
- Add GET /series/statuses endpoint for dynamic filter options
- Normalize series_metadata status values (migration 0036)
- Hide ComicVine provider tab when no API key configured
- Translate entire backoffice UI from English to French

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

infra/migrations/0034_add_metadata_batch.sql

@@ -0,0 +1,22 @@
+-- Add fallback_metadata_provider to libraries
+ALTER TABLE libraries ADD COLUMN fallback_metadata_provider TEXT;
+
+-- Table to store batch metadata job results (one row per series per job)
+CREATE TABLE metadata_batch_results (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    job_id UUID NOT NULL REFERENCES index_jobs(id) ON DELETE CASCADE,
+    library_id UUID NOT NULL REFERENCES libraries(id) ON DELETE CASCADE,
+    series_name TEXT NOT NULL,
+    status TEXT NOT NULL,  -- 'auto_matched', 'pending_review', 'no_results', 'too_many_results', 'low_confidence', 'already_linked', 'error'
+    provider_used TEXT,
+    fallback_used BOOLEAN NOT NULL DEFAULT FALSE,
+    candidates_count INTEGER NOT NULL DEFAULT 0,
+    best_confidence REAL,
+    best_candidate_json JSONB,
+    link_id UUID REFERENCES external_metadata_links(id) ON DELETE SET NULL,
+    error_message TEXT,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX idx_mbr_job_id ON metadata_batch_results(job_id);
+CREATE INDEX idx_mbr_status ON metadata_batch_results(status);

infra/migrations/0035_add_metadata_batch_job_type.sql

@@ -0,0 +1,5 @@
+-- Allow metadata_batch job type in index_jobs
+ALTER TABLE index_jobs
+  DROP CONSTRAINT IF EXISTS index_jobs_type_check,
+  ADD CONSTRAINT index_jobs_type_check
+    CHECK (type IN ('scan', 'rebuild', 'full_rebuild', 'thumbnail_rebuild', 'thumbnail_regenerate', 'cbr_to_cbz', 'metadata_batch'));

infra/migrations/0036_normalize_series_status.sql

@@ -0,0 +1,8 @@
+-- Normalize series_metadata.status values from provider-specific strings to standard enum values
+UPDATE series_metadata SET status = 'ongoing' WHERE LOWER(status) LIKE '%en cours%';
+UPDATE series_metadata SET status = 'ended' WHERE LOWER(status) LIKE '%finie%' OR LOWER(status) LIKE '%terminée%';
+UPDATE series_metadata SET status = 'hiatus' WHERE LOWER(status) LIKE '%hiatus%' OR LOWER(status) LIKE '%suspendue%';
+UPDATE series_metadata SET status = 'cancelled' WHERE LOWER(status) LIKE '%annulée%' OR LOWER(status) LIKE '%arrêtée%';
+UPDATE series_metadata SET status = 'upcoming' WHERE LOWER(status) LIKE '%not_yet_released%';
+UPDATE series_metadata SET status = 'ongoing' WHERE LOWER(status) = 'releasing';
+UPDATE series_metadata SET status = 'ended' WHERE LOWER(status) = 'finished';