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/api/src/jobs/bull.config.ts

@@ -1,4 +1,5 @@
 import { ConnectionOptions } from "bullmq";
+import { isOtelEnabled } from "../telemetry";
 
 export function getBullConnection(): ConnectionOptions {
   return {
@@ -8,6 +9,17 @@ export function getBullConnection(): ConnectionOptions {
   };
 }
 
+export function getBullTelemetry() {
+  if (!isOtelEnabled) return undefined;
+  try {
+    const { BullMQOtel } = require("bullmq-otel");
+    return new BullMQOtel("sase");
+  } catch (err) {
+    console.warn("[otel] BullMQ telemetry unavailable:", (err as Error).message);
+    return undefined;
+  }
+}
+
 export const QUEUE_NAMES = {
   EMEX_SCRAPE: "emex-scrape",
   SUBSCRIPTION_EXPIRY: "subscription-expiry",

apps/api/src/jobs/queues/emex-scrape.queue.ts

@@ -1,14 +1,16 @@
 import { Provider } from "@nestjs/common";
 import { Queue } from "bullmq";
-import { getBullConnection, QUEUE_NAMES } from "../bull.config";
+import { getBullConnection, getBullTelemetry, QUEUE_NAMES } from "../bull.config";
 
 export const EMEX_SCRAPE_QUEUE = "EMEX_SCRAPE_QUEUE";
 
 export const EmexScrapeQueueProvider: Provider = {
   provide: EMEX_SCRAPE_QUEUE,
   useFactory: () => {
+    const telemetry = getBullTelemetry();
     return new Queue(QUEUE_NAMES.EMEX_SCRAPE, {
       connection: getBullConnection(),
+      ...(telemetry ? { telemetry } : {}),
       defaultJobOptions: {
         attempts: 3,
         backoff: {

apps/api/src/jobs/queues/query-cleanup.queue.ts

@@ -1,14 +1,16 @@
 import { Provider } from "@nestjs/common";
 import { Queue } from "bullmq";
-import { getBullConnection, QUEUE_NAMES } from "../bull.config";
+import { getBullConnection, getBullTelemetry, QUEUE_NAMES } from "../bull.config";
 
 export const QUERY_CLEANUP_QUEUE = "QUERY_CLEANUP_QUEUE";
 
 export const QueryCleanupQueueProvider: Provider = {
   provide: QUERY_CLEANUP_QUEUE,
   useFactory: () => {
+    const telemetry = getBullTelemetry();
     return new Queue(QUEUE_NAMES.QUERY_CLEANUP, {
       connection: getBullConnection(),
+      ...(telemetry ? { telemetry } : {}),
       defaultJobOptions: {
         attempts: 2,
         backoff: {

apps/api/src/jobs/queues/subscription-expiry.queue.ts

@@ -1,14 +1,16 @@
 import { Provider } from "@nestjs/common";
 import { Queue } from "bullmq";
-import { getBullConnection, QUEUE_NAMES } from "../bull.config";
+import { getBullConnection, getBullTelemetry, QUEUE_NAMES } from "../bull.config";
 
 export const SUBSCRIPTION_EXPIRY_QUEUE = "SUBSCRIPTION_EXPIRY_QUEUE";
 
 export const SubscriptionExpiryQueueProvider: Provider = {
   provide: SUBSCRIPTION_EXPIRY_QUEUE,
   useFactory: () => {
+    const telemetry = getBullTelemetry();
     return new Queue(QUEUE_NAMES.SUBSCRIPTION_EXPIRY, {
       connection: getBullConnection(),
+      ...(telemetry ? { telemetry } : {}),
       defaultJobOptions: {
         attempts: 3,
         backoff: {