chore: remove internal docs from repo, update public documentation

Remove docs/superpowers/, .claude/ config, and PRD.md from version
control (kept locally via .gitignore). Update README, CHANGELOG,
VitePress docs, and .env.example to reflect recent features: Files
page, teams, admin settings, persistent storage, and various API
improvements.

apps/web/src/components/common/tool-card.tsx

@@ -15,6 +15,7 @@ export function ToolCard({ tool }: ToolCardProps) {
   return (
     <div className="group flex items-center gap-3 relative">
       <button
+        type="button"
         className="opacity-0 group-hover:opacity-100 transition-opacity absolute -left-5"
         title="Add to favourites"
       >