Refactor: Move Vaultik struct and methods to internal/vaultik package

- Created new internal/vaultik package with unified Vaultik struct
- Moved all command methods (snapshot, info, prune, verify) from CLI to vaultik package
- Implemented single constructor that handles crypto capabilities automatically
- Added CanDecrypt() method to check if decryption is available
- Updated all CLI commands to use the new vaultik.Vaultik struct
- Removed old fragmented App structs and WithCrypto wrapper
- Fixed context management - Vaultik now owns its context lifecycle
- Cleaned up package imports and dependencies

This creates a cleaner separation between CLI/Cobra code and business logic,
with all vaultik operations now centralized in the internal/vaultik package.

internal/database/snapshots.go

@@ -337,6 +337,24 @@ func (r *SnapshotRepository) GetBlobHashes(ctx context.Context, snapshotID strin
 	return blobs, rows.Err()
 }
 
+// GetSnapshotTotalCompressedSize returns the total compressed size of all blobs referenced by a snapshot
+func (r *SnapshotRepository) GetSnapshotTotalCompressedSize(ctx context.Context, snapshotID string) (int64, error) {
+	query := `
+		SELECT COALESCE(SUM(b.compressed_size), 0)
+		FROM snapshot_blobs sb
+		JOIN blobs b ON sb.blob_hash = b.blob_hash
+		WHERE sb.snapshot_id = ?
+	`
+
+	var totalSize int64
+	err := r.db.conn.QueryRowContext(ctx, query, snapshotID).Scan(&totalSize)
+	if err != nil {
+		return 0, fmt.Errorf("querying total compressed size: %w", err)
+	}
+
+	return totalSize, nil
+}
+
 // GetIncompleteSnapshots returns all snapshots that haven't been completed
 func (r *SnapshotRepository) GetIncompleteSnapshots(ctx context.Context) ([]*Snapshot, error) {
 	query := `
@@ -474,3 +492,15 @@ func (r *SnapshotRepository) DeleteSnapshotBlobs(ctx context.Context, snapshotID
 
 	return nil
 }
+
+// DeleteSnapshotUploads removes all uploads entries for a snapshot
+func (r *SnapshotRepository) DeleteSnapshotUploads(ctx context.Context, snapshotID string) error {
+	query := `DELETE FROM uploads WHERE snapshot_id = ?`
+
+	_, err := r.db.ExecWithLog(ctx, query, snapshotID)
+	if err != nil {
+		return fmt.Errorf("deleting snapshot uploads: %w", err)
+	}
+
+	return nil
+}