chore: add nextjs template

Dockerfile.agent.example

@@ -0,0 +1,16 @@
+FROM node:20-slim
+
+WORKDIR /app
+
+# Install dependencies first (for better caching)
+COPY package*.json ./
+RUN npm install
+
+# Copy application files
+COPY . .
+
+# Expose Next.js dev port
+EXPOSE 3000
+
+# Start Next.js in dev mode with hot reload
+CMD ["npm", "run", "dev"]