Implement CLI skeleton with cobra and fx dependency injection

- Set up cobra CLI with all commands (backup, restore, prune, verify, fetch)
- Integrate uber/fx for dependency injection and lifecycle management
- Add globals package with build-time variables (Version, Commit)
- Implement config loading from YAML with validation
- Create core data models (FileInfo, ChunkInfo, BlobInfo, Snapshot)
- Add Makefile with build, test, lint, and clean targets
- Include minimal test suite for compilation verification
- Update documentation with --quick flag for verify command
- Fix markdown numbering in implementation TODO

internal/cli/root.go

@@ -0,0 +1,28 @@
+package cli
+
+import (
+	"github.com/spf13/cobra"
+)
+
+// NewRootCommand creates the root cobra command
+func NewRootCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "vaultik",
+		Short: "Secure incremental backup tool with asymmetric encryption",
+		Long: `vaultik is a secure incremental backup daemon that encrypts data using age
+public keys and uploads to S3-compatible storage. No private keys are needed
+on the source system.`,
+		SilenceUsage: true,
+	}
+
+	// Add subcommands
+	cmd.AddCommand(
+		NewBackupCommand(),
+		NewRestoreCommand(),
+		NewPruneCommand(),
+		NewVerifyCommand(),
+		NewFetchCommand(),
+	)
+
+	return cmd
+}