feat: add monitoring dashboard (Prometheus + Grafana + Umami + Admin)

Phase 1: Infrastructure
- Add docker/prometheus/prometheus.yml with scrape configs for all services
- Add docker/grafana/provisioning for auto-configured datasources
- Add docker/grafana/dashboards (system-overview, backends-docker)
- Update docker-compose.macmini.yml with monitoring services:
  - prometheus, grafana, node-exporter, cadvisor
  - postgres-exporter, redis-exporter, umami
- Add grafana.mana.how and analytics.mana.how to Caddyfile

Phase 2: Backend Metrics
- Create packages/shared-nestjs-metrics with:
  - MetricsModule (auto /metrics endpoint)
  - MetricsService (Counter, Histogram, Gauge helpers)
  - MetricsMiddleware (auto HTTP request tracking)

Phase 3: Umami Web Analytics
- Add Umami tracking scripts to all landing pages
- Add Umami tracking scripts to all web apps
- Create scripts/mac-mini/setup-umami-db.sh

Phase 4: Admin Dashboard (ManaCore Web)
- Add admin routes: /admin, /admin/users, /admin/system
- Create StatCard, QuickLinks, UserTable components
- Add Admin link to navigation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker/prometheus/prometheus.yml

@@ -0,0 +1,88 @@
+# ManaCore Prometheus Configuration
+# Scrapes metrics from all services
+
+global:
+  scrape_interval: 15s
+  evaluation_interval: 15s
+
+# Alertmanager configuration (optional, for future use)
+# alerting:
+#   alertmanagers:
+#     - static_configs:
+#         - targets: []
+
+scrape_configs:
+  # Prometheus self-monitoring
+  - job_name: 'prometheus'
+    static_configs:
+      - targets: ['localhost:9090']
+
+  # Host system metrics via node-exporter
+  - job_name: 'node'
+    static_configs:
+      - targets: ['node-exporter:9100']
+    relabel_configs:
+      - source_labels: [__address__]
+        target_label: instance
+        replacement: 'mac-mini'
+
+  # Docker container metrics via cAdvisor
+  - job_name: 'cadvisor'
+    static_configs:
+      - targets: ['cadvisor:8080']
+
+  # PostgreSQL metrics
+  - job_name: 'postgres'
+    static_configs:
+      - targets: ['postgres-exporter:9187']
+
+  # Redis metrics
+  - job_name: 'redis'
+    static_configs:
+      - targets: ['redis-exporter:9121']
+
+  # ============================================
+  # Application Backends (after /metrics added)
+  # ============================================
+
+  # Auth Service
+  - job_name: 'mana-core-auth'
+    static_configs:
+      - targets: ['mana-core-auth:3001']
+    metrics_path: '/metrics'
+    scrape_interval: 30s
+
+  # Chat Backend
+  - job_name: 'chat-backend'
+    static_configs:
+      - targets: ['chat-backend:3002']
+    metrics_path: '/metrics'
+    scrape_interval: 30s
+
+  # Todo Backend
+  - job_name: 'todo-backend'
+    static_configs:
+      - targets: ['todo-backend:3018']
+    metrics_path: '/metrics'
+    scrape_interval: 30s
+
+  # Calendar Backend
+  - job_name: 'calendar-backend'
+    static_configs:
+      - targets: ['calendar-backend:3016']
+    metrics_path: '/metrics'
+    scrape_interval: 30s
+
+  # Clock Backend
+  - job_name: 'clock-backend'
+    static_configs:
+      - targets: ['clock-backend:3017']
+    metrics_path: '/metrics'
+    scrape_interval: 30s
+
+  # Contacts Backend
+  - job_name: 'contacts-backend'
+    static_configs:
+      - targets: ['contacts-backend:3015']
+    metrics_path: '/metrics'
+    scrape_interval: 30s