Adds `GET /` to rpast routes. Without it, /rpast on a space subdomain
404'd because the sub-app had no root handler. Now matches the rNotes
pattern: bare domain → marketing landing, in-space URL → app shell with
<rpast-viewer>.
- New rpast module renders a cross-rApp personal timeline
- shared/markwhen/ projection layer hydrates from syncServer docs
- rCal gets a Timeline applet wiring into the same markwhen view
- rstack-markwhen-view component for embedding elsewhere
- Smoke-test fixtures under output/ and scripts/smoke-rpast.ts
- Adds @markwhen/{parser,timeline,calendar,mw} deps
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Jeff Emmett