chore: convert submodules to standard directories for true monorepo structure

vibn-frontend/instrumentation-client.ts

@@ -0,0 +1,35 @@
+/**
+ * Next.js client-side instrumentation. Runs in the browser bundle
+ * before the app renders. Captures unhandled exceptions, promise
+ * rejections, and router navigation errors. Also enables Sentry
+ * Session Replay (free tier) so we can rewatch what the user was
+ * doing when an error fired — invaluable for solo-dev beta debugging.
+ */
+
+import * as Sentry from '@sentry/nextjs';
+
+Sentry.init({
+  dsn: process.env.NEXT_PUBLIC_SENTRY_DSN,
+  enabled: Boolean(process.env.NEXT_PUBLIC_SENTRY_DSN),
+  environment: process.env.NEXT_PUBLIC_SENTRY_ENVIRONMENT || process.env.NODE_ENV,
+
+  tracesSampleRate: 1.0,
+
+  // Session Replay: record a video-like reconstruction of the user's
+  // tab on every error, plus 10% of healthy sessions for context.
+  // Free tier covers this comfortably.
+  replaysSessionSampleRate: 0.1,
+  replaysOnErrorSampleRate: 1.0,
+
+  integrations: [
+    Sentry.replayIntegration({
+      // Mask all text/inputs by default — beta users may type
+      // anything into chat. Selectively unmask later if needed.
+      maskAllText: true,
+      blockAllMedia: true,
+    }),
+  ],
+});
+
+// Required for client-side router transition errors to reach Sentry.
+export const onRouterTransitionStart = Sentry.captureRouterTransitionStart;