fix: add next-pwa type declaration for strict tsc

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

workspace/next-app/next-pwa.d.ts

@@ -0,0 +1,16 @@
+declare module "next-pwa" {
+  import type { NextConfig } from "next";
+
+  interface PWAConfig {
+    dest?: string;
+    disable?: boolean;
+    register?: boolean;
+    scope?: string;
+    sw?: string;
+    [key: string]: unknown;
+  }
+
+  export default function withPWA(
+    config?: PWAConfig,
+  ): (nextConfig: NextConfig) => NextConfig;
+}