Initial scaffold: offertesysteem (clients, projects, quotes, quote_items)

- Next.js 15 + TypeScript + Tailwind, standalone output
- SQLite schema: users, clients, projects, quotes, quote_items
- HMAC-signed sessie-cookie auth
- Dockerfile (Node 22 Alpine, multi-stage)
- create-admin script
- Doel: portal.rikxplatform.nl

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

.env.example

@@ -0,0 +1,10 @@
+SESSION_SECRET=vervang-dit-met-een-willekeurige-string-van-64-tekens
+DB_PATH=./data/app.db
+NODE_ENV=development
+
+# Email (voor workflow-notificaties)
+SMTP_HOST=
+SMTP_PORT=587
+SMTP_USER=
+SMTP_PASS=
+SMTP_FROM=noreply@rikx.nl