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/tempo-values.yaml

@@ -0,0 +1,61 @@
+# Grafana Tempo - Monolithic mode (single binary)
+# Chart: grafana/tempo
+# Recebe traces do OpenTelemetry Collector e armazena localmente
+
+# Single replica - minimal for workshop on Hetzner CAX11
+replicas: 1
+
+tempo:
+  # Storage config - local filesystem
+  storage:
+    trace:
+      backend: local
+      local:
+        path: /var/tempo/traces
+      wal:
+        path: /var/tempo/wal
+
+  # Retention (maps to compactor.compaction.block_retention in tempo config)
+  retention: 168h  # 7 days
+
+  # Receive traces via OTLP only (disable other receivers)
+  receivers:
+    otlp:
+      protocols:
+        grpc:
+          endpoint: "0.0.0.0:4317"
+        http:
+          endpoint: "0.0.0.0:4318"
+
+  # Metrics generator - generates span metrics for Victoria Metrics
+  metricsGenerator:
+    enabled: true
+    remoteWriteUrl: "http://vmsingle-monitoring-victoria-metrics-k8s-stack.monitoring:8429/api/v1/write"
+    processor:
+      service_graphs:
+        dimensions:
+          - http.method
+          - http.route
+        enable_client_server_prefix: true
+        max_items: 10000
+      span_metrics:
+        dimensions:
+          - http.method
+          - http.route
+          - http.status_code
+        enable_target_info: true
+
+  # Resources for tempo container (under tempo key for this chart)
+  resources:
+    requests:
+      cpu: 100m
+      memory: 256Mi
+    limits:
+      cpu: 500m
+      memory: 512Mi
+
+# Persistence via Hetzner CSI
+persistence:
+  enabled: true
+  size: 10Gi
+  storageClassName: hcloud-volumes