aula-15: implementação completa APM (Tempo + OTel + demo app)

Componentes:
- tempo-values.yaml: Grafana Tempo monolithic, 256Mi, 10Gi PVC
- otel-collector-values.yaml: recebe OTLP, exporta traces→Tempo,
  gera span metrics (RED)→Victoria Metrics via spanmetrics connector
- demo-app/: Node.js com rotas /fast (1 query), /slow (N+1, 51 queries),
  /fixed (JOIN), auto-instrumentado com OpenTelemetry
- alerts/latency-alerts.yaml: VMRule com Doherty threshold (p95>400ms)
- setup.sh: instala Tempo, OTel Collector, configura Grafana datasource,
  deploy demo app via ConfigMap (sem Docker build necessário)
- cleanup.sh: remove apenas recursos da aula-15, preserva aula-12

Zero hardcoded hostnames. Tudo via .env e placeholders.

aula-15/demo-app/k8s/deployment.yaml

@@ -0,0 +1,64 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: demo-app
+  namespace: demo
+  labels:
+    app: demo-app
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: demo-app
+  template:
+    metadata:
+      labels:
+        app: demo-app
+    spec:
+      containers:
+        - name: demo-app
+          image: REGISTRY_PLACEHOLDER/IMAGE_NAME_PLACEHOLDER:latest
+          ports:
+            - containerPort: 3000
+          env:
+            - name: PG_HOST
+              value: demo-postgresql
+            - name: PG_PORT
+              value: "5432"
+            - name: PG_USER
+              value: demo
+            - name: PG_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: demo-postgresql
+                  key: POSTGRES_PASSWORD
+            - name: PG_DATABASE
+              value: demo
+            - name: OTEL_EXPORTER_OTLP_ENDPOINT
+              value: http://otel-collector-opentelemetry-collector.monitoring:4317
+            - name: OTEL_SERVICE_NAME
+              value: demo-app
+            - name: NODE_OPTIONS
+              value: "--require ./tracing.js"
+          resources:
+            requests:
+              memory: "64Mi"
+              cpu: "50m"
+            limits:
+              memory: "128Mi"
+          livenessProbe:
+            httpGet:
+              path: /health
+              port: 3000
+            initialDelaySeconds: 10
+            periodSeconds: 10
+            timeoutSeconds: 3
+            failureThreshold: 3
+          readinessProbe:
+            httpGet:
+              path: /health
+              port: 3000
+            initialDelaySeconds: 5
+            periodSeconds: 5
+            timeoutSeconds: 3
+            failureThreshold: 3