feat: Phase 0 walking skeleton — monorepo, API, web, ML stub

Sets up the full Phase 0 foundation:

- pnpm workspaces + turbo build graph; native module build approval
- packages/shared-types: HTTP contracts (Tip, Auth, Integrations, User)
- services/api: Express modular monolith with better-sqlite3/drizzle
  - auth: Google OAuth2 + PKCE via openid-client v6, cookie sessions
  - integrations: Todoist OAuth2 connect/disconnect, token vault
  - recommender: RandomPolicy over Todoist tasks, feedback sink
  - user: profile, consent capture, full account deletion (GDPR)
- apps/web: Next.js 15, three pages (sign-in → connect → tip)
  - tip page: black canvas, hold-to-act gesture, action sheet
  - PWA manifest + theme
- ml/serving: FastAPI stub implementing the POST /score contract
- infra: docker-compose (core/full profiles), Dockerfiles, CI skeleton
- .env.example with all required vars documented

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/next.config.ts

@@ -0,0 +1,14 @@
+import type { NextConfig } from 'next';
+
+const nextConfig: NextConfig = {
+  async rewrites() {
+    return [
+      {
+        source: '/api/:path*',
+        destination: `${process.env.NEXT_PUBLIC_API_URL ?? 'http://localhost:3001'}/api/:path*`,
+      },
+    ];
+  },
+};
+
+export default nextConfig;