chore: add nextjs template

frontend-nextjs/app/api/products/[id]/route.ts

@@ -0,0 +1,41 @@
+import { NextRequest, NextResponse } from "next/server";
+import { Pool } from "pg";
+
+const pool = new Pool({
+  host: process.env.DB_HOST || "127.0.0.1",
+  port: parseInt(process.env.DB_PORT || "5432"),
+  user: process.env.DB_USER || "myuser",
+  password: process.env.DB_PASSWORD || "mypassword",
+  database: process.env.DB_DATABASE || "mydb",
+});
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: { id: string } }
+) {
+  try {
+    const { id } = params;
+
+    const result = await pool.query(
+      `SELECT id, title, price_cents, slug, description
+       FROM products
+       WHERE id = $1`,
+      [id]
+    );
+
+    if (result.rows.length === 0) {
+      return NextResponse.json(
+        { error: "Product not found" },
+        { status: 404 }
+      );
+    }
+
+    return NextResponse.json(result.rows[0]);
+  } catch (error) {
+    console.error("Error fetching product:", error);
+    return NextResponse.json(
+      { error: "Failed to fetch product" },
+      { status: 500 }
+    );
+  }
+}