feat(cli): integrate zen-modules sync into project initialization

- add postinstall, dev, and build scripts to run `zen-modules sync`
- append `app/.zen/modules.generated.js` to .gitignore during init
- add generated modules file template with empty modules export
- import modules.generated.js in app layout and pass modules to initializeZen

templates/instrumentation.js

@@ -1,6 +1,7 @@
 export async function register() {
   if (process.env.NEXT_RUNTIME === 'nodejs') {
     const { initializeZen } = await import('@zen/core');
-    await initializeZen();
+    const { modules } = await import('./app/.zen/modules.generated.js');
+    await initializeZen({ modules });
   }
 }