Add exclude patterns, snapshot prune, and other improvements

- Implement exclude patterns with anchored pattern support:
  - Patterns starting with / only match from root of source dir
  - Unanchored patterns match anywhere in path
  - Support for glob patterns (*.log, .*, **/*.pack)
  - Directory patterns skip entire subtrees
  - Add gobwas/glob dependency for pattern matching
  - Add 16 comprehensive tests for exclude functionality

- Add snapshot prune command to clean orphaned data:
  - Removes incomplete snapshots from database
  - Cleans orphaned files, chunks, and blobs
  - Runs automatically at backup start for consistency

- Add snapshot remove command for deleting snapshots

- Add VAULTIK_AGE_SECRET_KEY environment variable support

- Fix duplicate fx module provider in restore command

- Change snapshot ID format to hostname_YYYY-MM-DDTHH:MM:SSZ

internal/database/chunk_files.go

@@ -132,3 +132,80 @@ func (r *ChunkFileRepository) DeleteByFileID(ctx context.Context, tx *sql.Tx, fi
 
 	return nil
 }
+
+// DeleteByFileIDs deletes all chunk_files for multiple files in a single statement.
+func (r *ChunkFileRepository) DeleteByFileIDs(ctx context.Context, tx *sql.Tx, fileIDs []string) error {
+	if len(fileIDs) == 0 {
+		return nil
+	}
+
+	// Batch at 500 to stay within SQLite's variable limit
+	const batchSize = 500
+
+	for i := 0; i < len(fileIDs); i += batchSize {
+		end := i + batchSize
+		if end > len(fileIDs) {
+			end = len(fileIDs)
+		}
+		batch := fileIDs[i:end]
+
+		query := "DELETE FROM chunk_files WHERE file_id IN (?" + repeatPlaceholder(len(batch)-1) + ")"
+		args := make([]interface{}, len(batch))
+		for j, id := range batch {
+			args[j] = id
+		}
+
+		var err error
+		if tx != nil {
+			_, err = tx.ExecContext(ctx, query, args...)
+		} else {
+			_, err = r.db.ExecWithLog(ctx, query, args...)
+		}
+		if err != nil {
+			return fmt.Errorf("batch deleting chunk_files: %w", err)
+		}
+	}
+
+	return nil
+}
+
+// CreateBatch inserts multiple chunk_files in a single statement for efficiency.
+func (r *ChunkFileRepository) CreateBatch(ctx context.Context, tx *sql.Tx, cfs []ChunkFile) error {
+	if len(cfs) == 0 {
+		return nil
+	}
+
+	// Each ChunkFile has 4 values, so batch at 200 to be safe with SQLite's variable limit
+	const batchSize = 200
+
+	for i := 0; i < len(cfs); i += batchSize {
+		end := i + batchSize
+		if end > len(cfs) {
+			end = len(cfs)
+		}
+		batch := cfs[i:end]
+
+		query := "INSERT INTO chunk_files (chunk_hash, file_id, file_offset, length) VALUES "
+		args := make([]interface{}, 0, len(batch)*4)
+		for j, cf := range batch {
+			if j > 0 {
+				query += ", "
+			}
+			query += "(?, ?, ?, ?)"
+			args = append(args, cf.ChunkHash, cf.FileID, cf.FileOffset, cf.Length)
+		}
+		query += " ON CONFLICT(chunk_hash, file_id) DO NOTHING"
+
+		var err error
+		if tx != nil {
+			_, err = tx.ExecContext(ctx, query, args...)
+		} else {
+			_, err = r.db.ExecWithLog(ctx, query, args...)
+		}
+		if err != nil {
+			return fmt.Errorf("batch inserting chunk_files: %w", err)
+		}
+	}
+
+	return nil
+}