Fix deep scan wiping track enrichment data and not updating file paths

INSERT OR REPLACE on existing tracks was deleting the entire row and
reinserting only 9 columns, nuking spotify_track_id, deezer_id, isrc,
bpm, musicbrainz IDs, and ~15 other enrichment columns every scan.

Now uses UPDATE for existing tracks (preserves all enrichment) and
INSERT only for new tracks. Also ensures file_path gets updated from
the media server on each scan, fixing stale paths for users whose
files were moved/reorganized.

database/music_database.py

@@ -3730,16 +3730,27 @@ class MusicDatabase:
                 if file_path is None and hasattr(track_obj, 'suffix') and track_obj.suffix:
                     file_path = f"{track_obj.title}.{track_obj.suffix}"
                 
-                # Check if this is a genuinely new track (for history logging)
+                # Check if track already exists — UPDATE to preserve enrichment columns,
+                # INSERT only for genuinely new tracks
                 cursor.execute("SELECT 1 FROM tracks WHERE id = ? LIMIT 1", (track_id,))
                 is_new_track = cursor.fetchone() is None
 
-                # Use INSERT OR REPLACE to handle duplicate IDs gracefully
-                cursor.execute("""
-                    INSERT OR REPLACE INTO tracks
-                    (id, album_id, artist_id, title, track_number, duration, file_path, bitrate, server_source, updated_at)
-                    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, CURRENT_TIMESTAMP)
-                """, (track_id, album_id, artist_id, title, track_number, duration, file_path, bitrate, server_source))
+                if is_new_track:
+                    cursor.execute("""
+                        INSERT INTO tracks
+                        (id, album_id, artist_id, title, track_number, duration, file_path, bitrate, server_source, updated_at)
+                        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, CURRENT_TIMESTAMP)
+                    """, (track_id, album_id, artist_id, title, track_number, duration, file_path, bitrate, server_source))
+                else:
+                    # Update server-provided fields only — preserves spotify_track_id, deezer_id,
+                    # isrc, bpm, musicbrainz IDs, and all other enrichment data
+                    cursor.execute("""
+                        UPDATE tracks
+                        SET album_id = ?, artist_id = ?, title = ?, track_number = ?,
+                            duration = ?, file_path = ?, bitrate = ?, server_source = ?,
+                            updated_at = CURRENT_TIMESTAMP
+                        WHERE id = ?
+                    """, (album_id, artist_id, title, track_number, duration, file_path, bitrate, server_source, track_id))
 
                 conn.commit()