feat: add OpenTelemetry observability, Faro frontend monitoring, remove legacy Next.js app

- Add OpenTelemetry SDK with tracing, metrics, and OTLP export for API and worker
- Integrate Grafana Faro for frontend real-user monitoring
- Instrument health checks, database, Bull queues, and HTTP exception filter
- Add Grafana dashboard JSON for service overview
- Remove deprecated apps/web-nj (Next.js) — fully replaced by Vite+React frontend
- Update nginx config with OTEL collector proxy
- Minor UI fixes in schema viewer, category components, and subscription flow

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/package.json

@@ -15,6 +15,8 @@
     "clean": "rm -rf dist"
   },
   "dependencies": {
+    "@grafana/faro-web-sdk": "^2.2.4",
+    "@grafana/faro-web-tracing": "^2.2.4",
     "@remotion/player": "^4.0.422",
     "@sase/shared": "workspace:*",
     "@sase/ui": "workspace:*",