infra: add Docker Compose setup for local development

- Configure PostgreSQL 18 and Valkey 9.1 services
- Create multi-stage Dockerfiles for API and Web apps
- Set up pnpm workspace support in container builds
- Configure hot reload via volume mounts for both services
- Add healthchecks for service orchestration
- Support dev/production stage targets (tsx watch vs compiled)

documentation/notes.md

@@ -0,0 +1,3 @@
+# notes
+
+- pinning dependencies in package.json files

documentation/roadmap.md

@@ -17,7 +17,7 @@ Each phase produces a working, deployable increment. Nothing is built speculativ
 - [x] Scaffold Vite + React app with TanStack Router (single root route)
 - [x] Configure Drizzle ORM + connection to local PostgreSQL
 - [x] Write first migration (empty — just validates the pipeline works)
-- [ ] `docker-compose.yml` for local dev: `api`, `web`, `postgres`, `valkey`
+- [x] `docker-compose.yml` for local dev: `api`, `web`, `postgres`, `valkey`
 - [ ] `.env.example` files for `apps/api` and `apps/web`
 - [ ] update decisions.md
 

documentation/spec.md

@@ -24,9 +24,9 @@ A multiplayer English–Italian vocabulary trainer with a Duolingo-style quiz in
 | Styling              | Tailwind CSS + shadcn/ui      |
 | Backend              | Node.js, Express, TypeScript  |
 | Realtime             | WebSockets (`ws` library)     |
-| Database             | PostgreSQL 16                 |
+| Database             | PostgreSQL 18                 |
 | ORM                  | Drizzle ORM                   |
-| Cache / Queue        | Valkey 8                      |
+| Cache / Queue        | Valkey 9                      |
 | Auth                 | OpenAuth (Google + GitHub)    |
 | Validation           | Zod (shared schemas)          |
 | Testing              | Vitest, React Testing Library |