Build Reflow web demo

[lsclin]

What changed

• initialize an Expo SDK 57, TypeScript, Expo Router, and React Native Web application
• add five mobile-first routes for Today, Inbox, Active, Calendar, and Review
• implement deterministic local Proposal generation, explicit task domain actions, and AsyncStorage persistence
• complete the capture-to-review workflow, month calendar scheduling, reset flow, and responsive shell
• add reducer, proposal, selector, and persistence tests plus project documentation

Why

This establishes the first runnable Reflow MVP for validating the core workflow before connecting real AI, accounts, or backend services.

Validation

• npm run typecheck
• npm run lint
• npm test — 4 suites, 11 tests passed
• npm run export:web — static export succeeded