refactor: move umami and sentry to server side

sentry.client.config.ts

@@ -1,13 +1,19 @@
 import * as Sentry from '@sentry/nextjs';
 
-const dsn = process.env.SENTRY_DSN;
+// We use a placeholder DSN on the client because the real DSN is injected
+// by our server-side relay at /errors/api/relay.
+// This keeps our environment clean of NEXT_PUBLIC_ variables.
+const CLIENT_DSN = 'https://public@errors.infra.mintel.me/1';
 
 Sentry.init({
-  dsn,
-  enabled: Boolean(dsn),
+  dsn: CLIENT_DSN,
+  // Relay events through our own server to hide the real DSN and bypass ad-blockers
+  tunnel: '/errors/api/relay',
+
+  // Enable even if no DSN is provided, because we have the tunnel
+  enabled: true,
+
   tracesSampleRate: 0,
-  // AdjustingreplaysOnErrorSampleRate to 1.0 to capture 100% of errors with replays if enabled
   replaysOnErrorSampleRate: 1.0,
   replaysSessionSampleRate: 0.1,
 });
-