fix(db): keep migration checksums stable

Issue #155 removed the sqlx 0.8 rebuild workarounds by editing migrations
0007, 0014 and 0021 in place. Editing an applied migration changes its
checksum, and `migrate()` refuses to run when one no longer matches what
`_sqlx_migrations` recorded, so the daemon exited on startup against any
database that had already applied them — production included.

The sqlx 0.9 bump is the fix and survives: a new migration can carry
`-- no-transaction` so `PRAGMA foreign_keys = OFF` holds and a table
rebuild stops cascade-deleting its children. Only the retroactive cleanup
of migrations that already ran is reverted, along with #153's
`CHECK (title <> '')`, which rode on the 0021 edit and needs a migration
of its own rather than a rewrite of history.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/arr-db/src/lib.rs

@@ -419,55 +419,6 @@ mod tests {
         );
     }
 
-    /// #153: an empty episode title takes the TBA placeholder during 0021's
-    /// backfill, and the rebuilt table's CHECK rejects new empty titles.
-    #[tokio::test]
-    async fn empty_episode_titles_are_backfilled_and_then_rejected() {
-        let dir = tempfile::tempdir().expect("tempdir");
-        let db = Db::connect(dir.path().join("arr.db"))
-            .await
-            .expect("connect");
-
-        MIGRATOR
-            .run_to(20, db.pool())
-            .await
-            .expect("migrations before the #153 backfill");
-
-        let series_id = sqlx::query(
-            "INSERT INTO series (tmdb_id, title, root_id)
-             SELECT 82728, 'Bluey', id FROM roots WHERE kind = 'tv' LIMIT 1",
-        )
-        .execute(db.pool())
-        .await
-        .expect("series")
-        .last_insert_rowid();
-        let season_id = sqlx::query("INSERT INTO seasons (series_id, number) VALUES (?, 1)")
-            .bind(series_id)
-            .execute(db.pool())
-            .await
-            .expect("season")
-            .last_insert_rowid();
-        sqlx::query("INSERT INTO episodes (season_id, number, title) VALUES (?, 1, '')")
-            .bind(season_id)
-            .execute(db.pool())
-            .await
-            .expect("empty title, valid before 0021");
-
-        db.migrate().await.expect("remaining migrations");
-
-        let title: String = sqlx::query_scalar("SELECT title FROM episodes")
-            .fetch_one(db.pool())
-            .await
-            .expect("episode row survives the rebuild");
-        assert_eq!(title, "TBA");
-
-        sqlx::query("INSERT INTO episodes (season_id, number, title) VALUES (?, 2, '')")
-            .bind(season_id)
-            .execute(db.pool())
-            .await
-            .expect_err("the rebuilt column rejects the empty string");
-    }
-
     #[tokio::test]
     async fn seeds_two_tv_roots_with_distinct_policies() {
         let (_dir, db) = fresh().await;