chore: add .worktrees/ and .superpowers/ to gitignore

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: dougrathbone

.gitignore

@@ -22,3 +22,9 @@ release/
 
 # TypeScript build info
 *.tsbuildinfo
+
+# Git worktrees
+.worktrees/
+
+# Superpowers brainstorm sessions
+.superpowers/