docs(prp): add PRP-11 ForecastLab Dashboard implementation plan (#48)

Comprehensive PRP for INITIAL-11 (The Face) with:
- 24 implementation tasks across 6 phases
- React 19 + Vite + shadcn/ui + TanStack Table/Query
- TypeScript types matching all backend API schemas
- Reusable DataTable with server-side pagination
- TimeSeriesChart component with Recharts
- WebSocket hook for agent chat streaming
- Complete documentation links and gotchas

Confidence score: 7.5/10 (chat depends on INITIAL-10)

Co-authored-by: Gabe@w7dev <gabor@w7-7.net>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: 3 people