fix(polecat): ensure nuke fully removes worktrees and branches

Two issues fixed:

1. Worktree directory cleanup used os.Remove() which only removes empty
   directories. Changed to os.RemoveAll() to clean up untracked files
   left behind by git worktree remove (overlay files, .beads/, etc.)

2. Branch deletion hardcoded mayor/rig but worktrees are created from
   .repo.git when using bare repo architecture. Now checks for bare
   repo first to match where the branch was created.

Fixes: gt-6ab3cm

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/polecat.go

@@ -1203,8 +1203,15 @@ func runPolecatNuke(cmd *cobra.Command, args []string) error {
 		}
 
 		// Step 4: Delete branch (if we know it)
+		// Use bare repo if it exists (matches where worktree was created), otherwise mayor/rig
 		if branchToDelete != "" {
-			repoGit := git.NewGit(filepath.Join(p.r.Path, "mayor", "rig"))
+			var repoGit *git.Git
+			bareRepoPath := filepath.Join(p.r.Path, ".repo.git")
+			if info, err := os.Stat(bareRepoPath); err == nil && info.IsDir() {
+				repoGit = git.NewGitWithDir(bareRepoPath, "")
+			} else {
+				repoGit = git.NewGit(filepath.Join(p.r.Path, "mayor", "rig"))
+			}
 			if err := repoGit.DeleteBranch(branchToDelete, true); err != nil {
 				// Non-fatal - branch might already be gone
 				fmt.Printf("  %s branch delete: %v\n", style.Dim.Render("○"), err)