feat(17-02): Dockerfile three-stage build, .dockerignore, .env.production.example

- Three-stage node:20-slim Dockerfile with --platform=linux/amd64 on all 3 FROM lines
- Non-root nextjs:nodejs user, seeds/ copied for form library, uploads/ dir pre-created
- HEALTHCHECK via wget pointing to /api/health, CMD node server.js
- .dockerignore excludes node_modules, .next, .git, .env*, uploads/, *.md
- .env.production.example with exactly 11 required vars (template, no real secrets, force-added past .env* glob)

teressa-copeland-homes/.env.production.example

@@ -0,0 +1,20 @@
+# Database
+DATABASE_URL=postgresql://user:password@host:5432/dbname?sslmode=require
+
+# Authentication
+SIGNING_JWT_SECRET=your-jwt-secret-here
+AUTH_SECRET=your-auth-secret-here
+AGENT_EMAIL=agent@example.com
+AGENT_PASSWORD=your-agent-password
+
+# SMTP (email delivery)
+CONTACT_EMAIL_USER=your-smtp-username
+CONTACT_EMAIL_PASS=your-smtp-password
+CONTACT_SMTP_HOST=smtp.example.com
+CONTACT_SMTP_PORT=465
+
+# OpenAI (AI field placement)
+OPENAI_API_KEY=sk-your-openai-key
+
+# Application
+APP_BASE_URL=https://yourdomain.com