fix: clean up empty parent directories after worktree removal (#41)

When using nested branch names like `fix/issue-x`, removing the worktree
leaves empty parent directories behind. Add a loop to both wt-rm and
wt-destroy that walks up from the target's parent, removing empty
directories until it hits the project root or a non-empty directory.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: davidpoblador

template/justfile

@@ -58,6 +58,13 @@ wt-rm target:
 
   git worktree remove "$TARGET"
 
+  # Remove empty parent directories left after worktree removal
+  DIR="$(dirname "$TARGET")"
+  while [ "$DIR" != "." ] && [ -d "$DIR" ] && [ -z "$(ls -A "$DIR")" ]; do
+    rmdir "$DIR"
+    DIR="$(dirname "$DIR")"
+  done
+
   if ! git branch -d "$TARGET" 2>/dev/null; then
     echo "Worktree removed but branch '$TARGET' has unmerged changes."
     echo "  To delete it anyway: git branch -D $TARGET"
@@ -79,6 +86,13 @@ wt-destroy target:
 
   git worktree remove "$TARGET" --force
 
+  # Remove empty parent directories left after worktree removal
+  DIR="$(dirname "$TARGET")"
+  while [ "$DIR" != "." ] && [ -d "$DIR" ] && [ -z "$(ls -A "$DIR")" ]; do
+    rmdir "$DIR"
+    DIR="$(dirname "$DIR")"
+  done
+
   git branch -D "$TARGET"
 
   if git remote | grep -q . && git ls-remote --exit-code --heads origin "$TARGET" >/dev/null 2>&1; then