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>

services/api/src/index.ts

@@ -0,0 +1,39 @@
+import 'dotenv/config';
+import express from 'express';
+import cookieParser from 'cookie-parser';
+import cors from 'cors';
+import { config } from './config.js';
+import { runMigrations } from './db/index.js';
+import { sessionMiddleware } from './middleware/session.js';
+import { authRouter } from './routes/auth.js';
+import { integrationsRouter } from './routes/integrations.js';
+import { recommenderRouter } from './routes/recommender.js';
+import { userRouter } from './routes/user.js';
+import { mkdir } from 'fs/promises';
+import { dirname } from 'path';
+
+await mkdir(dirname(config.DATABASE_PATH), { recursive: true });
+runMigrations();
+
+const app = express();
+
+app.use(
+  cors({
+    origin: config.WEB_BASE_URL,
+    credentials: true,
+  }),
+);
+app.use(express.json());
+app.use(cookieParser());
+app.use(sessionMiddleware);
+
+app.get('/health', (_req, res) => res.json({ ok: true }));
+
+app.use('/api/auth', authRouter);
+app.use('/api/integrations', integrationsRouter);
+app.use('/api', recommenderRouter);
+app.use('/api/user', userRouter);
+
+app.listen(config.PORT, () => {
+  console.log(`oO API listening on http://localhost:${config.PORT}`);
+});