Clarify health responses and required env vars

src/app/api/health/route.ts

@@ -5,11 +5,11 @@ export async function GET() {
   const timestamp = new Date().toISOString();
 
   return NextResponse.json({
-    ok: true,
     status: 'ok',
     service: 'prism-console',
-    timestamp,
-    ts: timestamp,
-    environment: serverConfig.environment
+    meta: {
+      timestamp,
+      environment: serverConfig.environment
+    }
   });
 }