Add custom types, version command, and restore --verify flag

- Add internal/types package with type-safe wrappers for IDs, hashes,
  paths, and credentials (FileID, BlobID, ChunkHash, etc.)
- Implement driver.Valuer and sql.Scanner for UUID-based types
- Add `vaultik version` command showing version, commit, go version
- Add `--verify` flag to restore command that checksums all restored
  files against expected chunk hashes with progress bar
- Remove fetch.go (dead code, functionality in restore)
- Clean up TODO.md, remove completed items
- Update all database and snapshot code to use new custom types

internal/cli/root.go

@@ -40,10 +40,10 @@ on the source system.`,
 		NewRestoreCommand(),
 		NewPruneCommand(),
 		NewVerifyCommand(),
-		NewFetchCommand(),
 		NewStoreCommand(),
 		NewSnapshotCommand(),
 		NewInfoCommand(),
+		NewVersionCommand(),
 	)
 
 	return cmd