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/db/index.ts

@@ -0,0 +1,53 @@
+import Database from 'better-sqlite3';
+import { drizzle } from 'drizzle-orm/better-sqlite3';
+import * as schema from './schema.js';
+import { config } from '../config.js';
+
+const sqlite = new Database(config.DATABASE_PATH);
+sqlite.pragma('journal_mode = WAL');
+sqlite.pragma('foreign_keys = ON');
+
+export const db = drizzle(sqlite, { schema });
+
+export function runMigrations() {
+  sqlite.exec(`
+    CREATE TABLE IF NOT EXISTS users (
+      id TEXT PRIMARY KEY,
+      email TEXT NOT NULL UNIQUE,
+      name TEXT,
+      image TEXT,
+      google_id TEXT UNIQUE,
+      consent_given INTEGER NOT NULL DEFAULT 0,
+      consent_at TEXT,
+      created_at TEXT NOT NULL,
+      deleted_at TEXT
+    );
+
+    CREATE TABLE IF NOT EXISTS integration_tokens (
+      id TEXT PRIMARY KEY,
+      user_id TEXT NOT NULL REFERENCES users(id),
+      provider TEXT NOT NULL,
+      access_token TEXT NOT NULL,
+      refresh_token TEXT,
+      expires_at TEXT,
+      connected_at TEXT NOT NULL,
+      UNIQUE(user_id, provider)
+    );
+
+    CREATE TABLE IF NOT EXISTS tip_feedback (
+      id TEXT PRIMARY KEY,
+      user_id TEXT NOT NULL REFERENCES users(id),
+      tip_id TEXT NOT NULL,
+      action TEXT NOT NULL,
+      source_id TEXT,
+      created_at TEXT NOT NULL
+    );
+
+    CREATE TABLE IF NOT EXISTS sessions (
+      id TEXT PRIMARY KEY,
+      user_id TEXT NOT NULL REFERENCES users(id),
+      expires_at TEXT NOT NULL,
+      created_at TEXT NOT NULL
+    );
+  `);
+}