refactor: deprecate 'self-update' in favor of 'self update'

Consolidates two self-update commands into one canonical version.

CHANGES:
- Added --dry-run flag to 'shells self update' command
- Deprecated 'shells self-update' (hyphenated) command
- Added deprecation warnings when using old command
- Hidden old command from help output

MIGRATION PATH:
- Old: shells self-update [--dry-run]
- New: shells self update [--dry-run] [--branch] [--source] etc.

The new 'shells self update' command provides:
- Better backup management (configurable max backups)
- Automatic binary validation
- Multiple configuration options
- Automatic database migrations
- More robust error handling via pkg/self updater

The old command still works but shows deprecation warnings.

DEPRECATION NOTICE:
Command: shells self-update
Status: Hidden, deprecated
Replacement: shells self update
Will be removed in: Future version

Users should update scripts and documentation to use the new command.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: CodeMonkeyCybersecurity

cmd/self.go

@@ -39,6 +39,7 @@ var (
 	updateSkipBackup   bool
 	updateSkipValidate bool
 	updateSourceDir    string
+	updateDryRun       bool
 )
 
 func init() {
@@ -47,6 +48,7 @@ func init() {
 	updateCmd.Flags().BoolVar(&updateSkipBackup, "skip-backup", false, "Skip backing up current binary")
 	updateCmd.Flags().BoolVar(&updateSkipValidate, "skip-validation", false, "Skip validating new binary (not recommended)")
 	updateCmd.Flags().StringVar(&updateSourceDir, "source", "/opt/shells", "Path to shells git repository")
+	updateCmd.Flags().BoolVar(&updateDryRun, "dry-run", false, "Check for updates without installing")
 
 	// Add subcommands
 	selfCmd.AddCommand(updateCmd)
@@ -69,6 +71,7 @@ func runUpdate(cmd *cobra.Command, args []string) error {
 	logger.Infow("Starting Shells self-update",
 		"branch", updateBranch,
 		"source_dir", updateSourceDir,
+		"dry_run", updateDryRun,
 	)
 
 	// Create updater configuration
@@ -85,6 +88,27 @@ func runUpdate(cmd *cobra.Command, args []string) error {
 	// Create updater
 	updater := self.NewShellsUpdater(logger, updateConfig)
 
+	// Dry run: just assess and report
+	if updateDryRun {
+		logger.Infow("Dry-run mode: assessing update availability")
+		state, err := updater.Assess()
+		if err != nil {
+			return fmt.Errorf("assessment failed: %w", err)
+		}
+
+		fmt.Println()
+		fmt.Println("Dry-run Assessment:")
+		fmt.Println("===================")
+		fmt.Printf("Source directory:  %s (exists: %v)\n", updateSourceDir, state.SourceExists)
+		fmt.Printf("Git repository:    %v\n", state.GitRepository)
+		fmt.Printf("Current version:   %s\n", state.CurrentVersion)
+		fmt.Printf("Binary path:       %s (exists: %v)\n", updateConfig.BinaryPath, state.BinaryExists)
+		fmt.Printf("Backup count:      %d\n", len(state.BackupPaths))
+		fmt.Println()
+		fmt.Println("Run without --dry-run to perform the actual update")
+		return nil
+	}
+
 	// Execute update
 	if err := updater.Update(); err != nil {
 		logger.Errorw("Self-update failed", "error", err)

cmd/self_update.go

@@ -21,21 +21,11 @@ var (
 )
 
 var selfUpdateCmd = &cobra.Command{
-	Use:   "self-update",
-	Short: "Update shells to the latest version from GitHub",
-	Long: `Update shells to the latest version by pulling from the GitHub repository,
-rebuilding the binary, and verifying the update with SHA256 checksums.
-
-This command will:
-1. Pull the latest code from the GitHub repository
-2. Run ./install.sh to rebuild and install the binary
-3. Compare SHA256 hashes to verify the update
-4. Report the size of the new binary
-
-The binary is always rebuilt after pulling to ensure you have the latest version,
-even if no new commits were pulled.
-
-Use --dry-run to preview the update without installing.`,
+	Use:        "self-update",
+	Short:      "DEPRECATED: Use 'shells self update' instead",
+	Long:       `DEPRECATED: This command is deprecated and will be removed in a future version.`,
+	Deprecated: "Use 'shells self update' instead, which provides better error handling, backup management, and database migrations.",
+	Hidden:     true,
 	PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
 		// Initialize config but skip database for self-update
 		return initConfig()
@@ -49,6 +39,16 @@ func init() {
 }
 
 func runSelfUpdate(cmd *cobra.Command, args []string) error {
+	fmt.Println()
+	fmt.Println("⚠️  WARNING: This command is DEPRECATED")
+	fmt.Println("   Use 'shells self update' instead for:")
+	fmt.Println("   - Better backup management")
+	fmt.Println("   - Automatic database migrations")
+	fmt.Println("   - Improved error handling")
+	fmt.Println()
+	fmt.Println("Continuing with deprecated command...")
+	fmt.Println()
+
 	log.Info("🔄 Starting shells self-update...", "component", "self_update")
 
 	// Get current binary path