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/frontend-mobile/services/faro.ts

@@ -0,0 +1,36 @@
+import { initializeFaro } from '@grafana/faro-react-native';
+
+let initialized = false;
+
+/**
+ * Initializes Grafana Faro RUM for the React Native app.
+ *
+ * Telemetry (crashes, JS errors, console, app-start, memory/ANR vitals,
+ * session + screen tracking) is sent OTLP/HTTP to the Alloy collector.
+ *
+ * NOTE: `@grafana/faro-react-native` ships a native module, so it requires a
+ * custom dev build / EAS build (not Expo Go). Initialization is wrapped in a
+ * try/catch so a collector outage never crashes the app.
+ */
+export function initFaro(): void {
+  if (initialized) return;
+  initialized = true;
+
+  try {
+    const url =
+      process.env.EXPO_PUBLIC_FARO_URL || 'http://grafana.hacecalor.net:4318';
+
+    initializeFaro({
+      app: {
+        name: 'farmafinder-mobile',
+        version: '1.0.0',
+        environment: __DEV__ ? 'development' : 'production',
+      },
+      url,
+      sessionTracking: { enabled: true },
+      // Crash/JS error/console capture are on by default.
+    });
+  } catch (err) {
+    console.warn('[faro] initialization failed:', err);
+  }
+}