Add _ensure_schema() to create SQLite tables if missing

- Creates all required tables (item, artist, album, avformat_info,
  store_info, item_to_container, track_size_calc) in Library.itdb
- Creates location table in Locations.itdb
- Called from Nano7Database.__init__(), so empty DB is always valid
- Fixes 'no such table: item' error on iPod with wiped DB

src/ipod_nano7_db.py

@@ -31,6 +31,76 @@ logger = logging.getLogger(__name__)
 
 MASTER_CONTAINER_PID = 203092939621887772  # "iPod" master playlist
 
+LIBRARY_SCHEMA_SQL = """
+CREATE TABLE IF NOT EXISTS item (
+    pid INTEGER PRIMARY KEY, media_kind INTEGER, is_song INTEGER,
+    date_modified INTEGER, year INTEGER, is_compilation INTEGER,
+    is_user_disabled INTEGER, remember_bookmark INTEGER,
+    exclude_from_shuffle INTEGER, part_of_gapless_album INTEGER,
+    chosen_by_auto_fill INTEGER, artwork_status INTEGER,
+    artwork_cache_id INTEGER, total_time_ms INTEGER,
+    track_number INTEGER, track_count INTEGER, disc_number INTEGER,
+    disc_count INTEGER, album_pid INTEGER, artist_pid INTEGER,
+    title TEXT, artist TEXT, album TEXT, album_artist TEXT,
+    sort_title TEXT, sort_artist TEXT, sort_album TEXT,
+    sort_album_artist TEXT, title_order INTEGER, artist_order INTEGER,
+    album_order INTEGER, physical_order INTEGER
+);
+
+CREATE TABLE IF NOT EXISTS artist (
+    pid INTEGER PRIMARY KEY, kind INTEGER, artwork_status INTEGER,
+    artwork_album_pid INTEGER, name TEXT, name_order INTEGER,
+    sort_name TEXT, is_unknown INTEGER, has_songs INTEGER,
+    has_music_videos INTEGER, has_non_compilation_tracks INTEGER,
+    album_count INTEGER
+);
+
+CREATE TABLE IF NOT EXISTS album (
+    pid INTEGER PRIMARY KEY, kind INTEGER, artwork_status INTEGER,
+    artwork_item_pid INTEGER, artist_pid INTEGER, user_rating INTEGER,
+    name TEXT, name_order INTEGER, all_compilations INTEGER,
+    feed_url TEXT, season_number INTEGER, is_unknown INTEGER,
+    has_songs INTEGER, has_music_videos INTEGER, sort_order INTEGER,
+    artist_order INTEGER, has_any_compilations INTEGER, sort_name TEXT,
+    artist_count_calc INTEGER, has_movies INTEGER, item_count INTEGER,
+    min_volume_normalization_energy INTEGER
+);
+
+CREATE TABLE IF NOT EXISTS avformat_info (
+    item_pid INTEGER, sub_id INTEGER, audio_format INTEGER,
+    bit_rate INTEGER, channels INTEGER, sample_rate INTEGER,
+    duration INTEGER, gapless_heuristic_info INTEGER,
+    gapless_encoding_delay INTEGER, gapless_encoding_drain INTEGER,
+    gapless_last_frame_resynch INTEGER, analysis_inhibit_flags INTEGER,
+    audio_fingerprint INTEGER, volume_normalization_energy INTEGER
+);
+
+CREATE TABLE IF NOT EXISTS store_info (
+    item_pid INTEGER PRIMARY KEY
+);
+
+CREATE TABLE IF NOT EXISTS item_to_container (
+    item_pid INTEGER, container_pid INTEGER, physical_order INTEGER,
+    shuffle_order INTEGER
+);
+
+CREATE TABLE IF NOT EXISTS track_size_calc (
+    kind TEXT PRIMARY KEY, size INTEGER DEFAULT 0
+);
+
+INSERT OR IGNORE INTO track_size_calc (kind, size) VALUES ('audio', 0);
+"""
+
+LOCATIONS_SCHEMA_SQL = """
+CREATE TABLE IF NOT EXISTS location (
+    item_pid INTEGER, sub_id INTEGER, base_location_id INTEGER,
+    location_type INTEGER, location TEXT, extension INTEGER,
+    kind_id INTEGER, date_created INTEGER, file_size INTEGER,
+    file_creator INTEGER, file_type INTEGER,
+    num_dir_levels_file INTEGER, num_dir_levels_lib INTEGER
+);
+"""
+
 
 class Nano7Database:
     """Manages iPod Nano 7 SQLite database and iTunesCDB"""
@@ -62,6 +132,25 @@ class Nano7Database:
             ".mp4": struct.unpack(">I", b"MP4 ")[0],
         }
 
+        self._ensure_schema()
+
+    def _ensure_schema(self) -> None:
+        """Create required tables in Library.itdb and Locations.itdb if missing."""
+        sqlite_path = self.sqlite_path
+        locations_path = self.locations_path
+
+        for db_path, schema in [(sqlite_path, LIBRARY_SCHEMA_SQL),
+                                 (locations_path, LOCATIONS_SCHEMA_SQL)]:
+            try:
+                os.makedirs(os.path.dirname(db_path), exist_ok=True)
+                conn = sqlite3.connect(db_path)
+                conn.executescript(schema)
+                conn.commit()
+                conn.close()
+                logger.info(f"Schema ensured in {os.path.basename(db_path)}")
+            except Exception as e:
+                logger.warning(f"Failed to ensure schema in {db_path}: {e}")
+
     def _detect_firewire_id(self) -> bytes:
         """Parse FirewireGuid from SysInfo file on the iPod."""
         sysinfo_path = os.path.join(