feat: set up monorepo scaffold with Yarn workspaces, Django API, React/Vite web, and Docker Compose

- Root package.json with Yarn workspaces (web, api)
- /web: React 19 + Vite 6 + @vitejs/plugin-react
  - index.html, src/main.jsx, src/App.jsx, vite.config.js
- /api: Django 5.x managed with uv
  - pyproject.toml with Django + psycopg2-binary
  - project/settings.py with PostgreSQL config from DATABASE_URL
  - project/urls.py, project/wsgi.py, manage.py
- docker-compose.yml with db (postgres:15), api, web services
  - Health check for db, live code volumes, dependency ordering
- Dockerfiles for both web (node:20-alpine) and api (python:3.12-slim)
- .gitignore updated for Python build artifacts and venv
- docs/implementation-issue-1-monorepo-scaffold.md

web/vite.config.js

@@ -0,0 +1,13 @@
+import { defineConfig } from "vite";
+import react from "@vitejs/plugin-react";
+
+export default defineConfig({
+  plugins: [react()],
+  server: {
+    host: "0.0.0.0",
+    port: 3000,
+    watch: {
+      usePolling: true,
+    },
+  },
+});