Add Docker deployment setup with health check endpoint

- Add multi-stage Dockerfile with standalone Next.js output
- Add docker-compose.yml with Caddy reverse proxy
- Add nginx configs for local and SSL setups
- Add Caddyfile for automatic HTTPS
- Add docker-entrypoint.sh for runtime config
- Add .env.example and .dockerignore
- Add comprehensive Docker README
- Add /api/health endpoint for container health checks
- Configure next.config.ts for standalone output

src/app/api/health/route.ts

@@ -0,0 +1,16 @@
+import { NextResponse } from 'next/server';
+
+/**
+ * Health check endpoint for Docker and monitoring
+ * Returns 200 OK when the application is running properly
+ */
+export async function GET() {
+    return NextResponse.json(
+        {
+            status: 'healthy',
+            timestamp: new Date().toISOString(),
+            service: 'synapsis',
+        },
+        { status: 200 }
+    );
+}