fix(schema): widen media_items.genre to TEXT

The genre column was VARCHAR(100), and the audio tag fallback stores the
file's raw genre atom verbatim. Libation writes Audible's category ladder
as one comma-joined string ("Politicians, Presidents & Heads of State,
United States, Russia, Communism & Socialism, International Relations" —
111 chars), so any such book failed its import or metadata update with
SQLSTATE 22001 (value too long), taking the whole row down with it.

VARCHAR -> TEXT is a metadata-only change in Postgres and safe to re-run;
the in-place ALTER follows the media_highlights position-widening
precedent so existing databases converge on restart (schema.sql runs on
every boot).

database/schema/schema.sql

@@ -174,7 +174,7 @@ CREATE TABLE IF NOT EXISTS media_items (
     language VARCHAR(10) DEFAULT 'en', -- Language code (ISO 639-1)
     edition VARCHAR(100), -- Edition information
     page_count INTEGER, -- Total page count
-    genre VARCHAR(100), -- Genre classification
+    genre TEXT, -- Genre classification (smart-genre shelf OR raw tag free text — Audible category strings exceed 100 chars)
     copyright_year INTEGER, -- Copyright/publication year
     goodreads_id VARCHAR(50), -- Goodreads identifier
     openlibrary_id VARCHAR(50), -- Open Library identifier
@@ -279,6 +279,14 @@ CREATE INDEX IF NOT EXISTS idx_media_items_contributors_gin ON media_items USING
 ALTER TABLE media_items ADD COLUMN IF NOT EXISTS tags_search TEXT[];
 ALTER TABLE media_items ADD COLUMN IF NOT EXISTS contributors_search TEXT[];
 
+-- Widen genre for existing databases: the audio tag fallback stores the
+-- raw file genre atom (Audible category strings exceed 100 chars —
+-- e.g. "Politicians, Presidents & Heads of State, United States, ..."),
+-- and VARCHAR(100) rejected the whole import/update at the database
+-- layer (SQLSTATE 22001). VARCHAR -> TEXT is a metadata-only change,
+-- safe to re-run (media_highlights position widening precedent).
+ALTER TABLE media_items ALTER COLUMN genre TYPE TEXT;
+
 -- Audiobook editorial facts (A2a): narrators are user-editable first-class
 -- (search/filter/badge surface); abridged rides along; audio_metadata keeps
 -- the scan-derived tech record (duration/codec/chapters).