feat: enable Sentry Session Replay for frontend monitoring

frontend/SENTRY_SETUP.md

@@ -32,6 +32,14 @@ This application is integrated with Sentry for comprehensive error tracking and
 - **Uncaught Exceptions**: JavaScript errors are automatically captured
 - **Network Errors**: Failed API requests are tracked
 - **Performance Issues**: Slow transactions and rendering issues
+- **Session Replay**: User interactions (clicks, scrolls, navigation) are captured for debugging
+
+### Session Replay Privacy Defaults
+- **PII Masking**: All text content in replay is masked (`maskAllText: true`)
+- **Media Blocking**: Images and video are blocked in replay (`blockAllMedia: true`)
+- **Sampling**:
+  - `replaysSessionSampleRate = 0.1` (10% of all sessions)
+  - `replaysOnErrorSampleRate = 1.0` (100% of sessions with errors)
 
 ### Manual Error Reporting
 Use the `useErrorReporting` hook for custom error tracking:

frontend/sentry.client.config.ts

@@ -2,9 +2,18 @@ import * as Sentry from "@sentry/nextjs";
 
 Sentry.init({
   dsn: process.env.NEXT_PUBLIC_SENTRY_DSN,
+  integrations: [
+    Sentry.replayIntegration({
+      // Privacy-by-default: mask text and block media in recordings.
+      maskAllText: true,
+      blockAllMedia: true,
+    }),
+  ],
   // Performance monitoring
   tracesSampleRate: 1.0,
-  // Session replay
+  // Session replay sampling
+  // - 10% of all sessions are recorded.
+  // - 100% of sessions with errors are recorded.
   replaysSessionSampleRate: 0.1,
   replaysOnErrorSampleRate: 1.0,
   // Environment