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/blob/packer.go

@@ -420,7 +420,6 @@ func (p *Packer) finalizeCurrentBlob() error {
 
 	// Call blob handler if set
 	if p.blobHandler != nil {
-		log.Debug("Invoking blob handler callback", "blob_hash", blobHash[:8]+"...")
 		// Reset file position for handler
 		if _, err := p.currentBlob.tempFile.Seek(0, io.SeekStart); err != nil {
 			p.cleanupTempFile()