Refactor App.tsx from god component to context-based architecture

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -13,6 +13,7 @@ pnpm test:watch         # Tests in watch mode
 pnpm typecheck          # tsc --build (project references)
 pnpm lint               # Biome lint
 pnpm format             # Biome format (writes)
+pnpm check:props        # Component prop count enforcement (max 8)
 pnpm --filter web dev   # Vite dev server (localhost:5173)
 pnpm --filter web build # Production build
 ```
@@ -71,6 +72,7 @@ docs/agents/               RPI skill artifacts (research reports, plans)
 - **Domain events** are plain data objects with a `type` discriminant — no classes.
 - **Tests** live in `packages/*/src/__tests__/*.test.ts`. Test pure functions directly; map acceptance scenarios and invariants from specs to individual `it()` blocks.
 - **Feature specs** live in `specs/NNN-feature-name/` with spec.md (and optionally plan.md, tasks.md for new work). Specs describe features, not individual changes. The project constitution is at `.specify/memory/constitution.md`.
+- **Component props** — max 8 explicitly declared props per component interface (enforced by `scripts/check-component-props.mjs`). Use React context for shared state; reserve props for per-instance config (data items, layout variants, refs).
 - **Quality gates** are enforced at pre-commit via Lefthook's `pnpm check` — the project's single earliest enforcement point. No gate may exist only as a CI step or manual process.
 
 ## Self-Review Checklist