chore: add .superpowers/ and test-results/ to gitignore

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

.gitignore

@@ -220,6 +220,12 @@ frontend/playwright-report/
 frontend/test-results/
 frontend/e2e/.auth/
 
+# Superpowers brainstorming mockups
+.superpowers/
+
+# Test results (root level)
+test-results/
+
 # Railway CLI (local tooling)
 node_modules/
 package.json