Phase 1 of Mini Apps: a new sidebar section that renders user apps as
premium tiles and opens each in a sandboxed iframe.
- New first-class 'apps' view wired through App.tsx (mirrors bg-tasks)
- 'Mini Apps' sidebar entry
- MiniAppFrame: sandboxed iframe host + window.rowboat bridge
(getData/onData, getState/setState, scoped callAction; actions stubbed)
- Self-contained vanilla apps (no CDN) so they render offline in the frame
- Sample apps: Twitter (X-style feed + topic filters), Newsletter Digest,
Competitor Watch
- Premium card gallery: accent themes, decorative patterns, ambient glow,
light/dark support
