Add confirmation when changing mobs dir with existing mobs

Abort init if user declines, with clear warning that worktrees
will remain on disk but codemob will no longer track them. Also
show init prompts for pre-feature configs missing repo_root.

Author: blipinsk

internal/mob/init.go

@@ -672,8 +672,14 @@ func setupRepo(reprompt bool) string {
 	if !isNew && oldMobsDir != cfg.MobsDirPath && len(cfg.Mobs) > 0 {
 		fmt.Println()
 		errMsg(fmt.Sprintf("You have %d existing mob(s) at the old location.", len(cfg.Mobs)))
-		fmt.Println("  They will be orphaned and removed from config on the next operation.")
-		fmt.Println("  Consider running 'codemob purge' first, or keep the current directory.")
+		fmt.Println("  codemob will no longer track them, but the worktrees will remain on disk.")
+		fmt.Println("  Run 'codemob purge' or 'codemob remove' first to clean them up.")
+		fmt.Print("\nContinue anyway? [y/N]: ")
+		input, _ = reader.ReadString('\n')
+		if v := strings.TrimSpace(strings.ToLower(input)); v != "y" && v != "yes" {
+			fmt.Println("Cancelled.")
+			return root
+		}
 	}
 
 	if resolved, err := filepath.EvalSymlinks(root); err == nil {