feat: add end-to-end observability (metrics, health, mobile RUM, dashboards, alerts)

- Backend: OTel metrics via OTLP -> Alloy -> Prometheus (OTEL_METRICS_EXPORTER=otlp)
- New business metrics (src/metrics.js): searches, CIMA latency/errors, cache
  hits/misses, logins, rate-limits, pharmacy writes/links, push sent/failed,
  DB + Redis timings/errors, HTTP req count/duration, heartbeat
- Backend health endpoints /healthz and /readyz
- Mobile (Expo): Grafana Faro RUM via @grafana/faro-react-native
- redis/postgres exporters in docker-compose + Prometheus scrape jobs
- Grafana dashboards (backend, datastores, mobile RUM, overview)
- Prometheus alert rules (farmafinder_*) -> existing Alertmanager (Telegram)
- Design/spec saved to docs/superpowers/specs/

apps/backend/redis-client.js

@@ -1,4 +1,5 @@
 import { createClient } from 'redis';
+import * as appMetrics from './src/metrics.js';
 
 // Create Redis client
 const redisClient = createClient({
@@ -11,6 +12,7 @@ const redisClient = createClient({
 
 // Error handler
 redisClient.on('error', (err) => {
+  appMetrics.redisErrorsTotal.add(1);
   console.error('Redis Client Error:', err);
 });
 
@@ -19,6 +21,27 @@ redisClient.on('connect', () => {
   console.log('✅ Connected to Redis');
 });
 
+// Instrument get/setEx with command duration (used by the CIMA cache path).
+const origGet = redisClient.get.bind(redisClient);
+redisClient.get = async (...args) => {
+  const start = performance.now();
+  try {
+    return await origGet(...args);
+  } finally {
+    appMetrics.redisCmdDuration.record(performance.now() - start);
+  }
+};
+
+const origSetEx = redisClient.setEx.bind(redisClient);
+redisClient.setEx = async (...args) => {
+  const start = performance.now();
+  try {
+    return await origSetEx(...args);
+  } finally {
+    appMetrics.redisCmdDuration.record(performance.now() - start);
+  }
+};
+
 // Connect to Redis
 await redisClient.connect();