Fix file content change handling and improve log messages

- Delete old file_chunks and chunk_files when file content changes
- Add DeleteByFileID method to ChunkFileRepository
- Add tests to verify old chunks are properly disassociated
- Make log messages more precise throughout scanner and snapshot
- Support metadata-only snapshots when no files have changed
- Add periodic status output during scan and snapshot operations
- Improve scan summary output with clearer information

internal/database/chunk_files.go

@@ -114,3 +114,21 @@ func (r *ChunkFileRepository) GetByFileID(ctx context.Context, fileID string) ([
 
 	return chunkFiles, rows.Err()
 }
+
+// DeleteByFileID deletes all chunk_files entries for a given file ID
+func (r *ChunkFileRepository) DeleteByFileID(ctx context.Context, tx *sql.Tx, fileID string) error {
+	query := `DELETE FROM chunk_files WHERE file_id = ?`
+
+	var err error
+	if tx != nil {
+		_, err = tx.ExecContext(ctx, query, fileID)
+	} else {
+		_, err = r.db.ExecWithLog(ctx, query, fileID)
+	}
+
+	if err != nil {
+		return fmt.Errorf("deleting chunk files: %w", err)
+	}
+
+	return nil
+}