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/snapshots.go

@@ -289,6 +289,46 @@ func (r *SnapshotRepository) AddFileByID(ctx context.Context, tx *sql.Tx, snapsh
 	return nil
 }
 
+// AddFilesByIDBatch adds multiple files to a snapshot in batched inserts
+func (r *SnapshotRepository) AddFilesByIDBatch(ctx context.Context, tx *sql.Tx, snapshotID string, fileIDs []string) error {
+	if len(fileIDs) == 0 {
+		return nil
+	}
+
+	// Each entry has 2 values, so batch at 400 to be safe
+	const batchSize = 400
+
+	for i := 0; i < len(fileIDs); i += batchSize {
+		end := i + batchSize
+		if end > len(fileIDs) {
+			end = len(fileIDs)
+		}
+		batch := fileIDs[i:end]
+
+		query := "INSERT OR IGNORE INTO snapshot_files (snapshot_id, file_id) VALUES "
+		args := make([]interface{}, 0, len(batch)*2)
+		for j, fileID := range batch {
+			if j > 0 {
+				query += ", "
+			}
+			query += "(?, ?)"
+			args = append(args, snapshotID, fileID)
+		}
+
+		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 adding files to snapshot: %w", err)
+		}
+	}
+
+	return nil
+}
+
 // AddBlob adds a blob to a snapshot
 func (r *SnapshotRepository) AddBlob(ctx context.Context, tx *sql.Tx, snapshotID string, blobID string, blobHash string) error {
 	query := `