feat: add VIP roster tracking and accountability reports

- Add isRosterOnly flag for VIPs who attend but don't need transportation
- Add VIP contact fields (phone, email) and emergency contact info
- Create Reports page under Admin menu with Accountability Roster
- Report shows all VIPs (active + roster-only) with contact/emergency info
- Export to CSV functionality for emergency preparedness
- VIP list filters roster-only by default with toggle to show
- VIP form includes collapsible contact/emergency section
- Fix first-user race condition with Serializable transaction
- Remove Traccar hardcoded default credentials
- Add feature flags endpoint for optional services

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

backend/.env.example

@@ -6,19 +6,19 @@ NODE_ENV=development
 FRONTEND_URL=http://localhost:5173
 
 # ============================================
-# Database Configuration
+# Database Configuration (required)
 # ============================================
 # Port 5433 is used to avoid conflicts with local PostgreSQL
 DATABASE_URL="postgresql://postgres:changeme@localhost:5433/vip_coordinator"
 
 # ============================================
-# Redis Configuration (Optional)
+# Redis Configuration (required)
 # ============================================
 # Port 6380 is used to avoid conflicts with local Redis
 REDIS_URL="redis://localhost:6380"
 
 # ============================================
-# Auth0 Configuration
+# Auth0 Configuration (required)
 # ============================================
 # Get these from your Auth0 dashboard:
 # 1. Create Application (Single Page Application)
@@ -29,6 +29,16 @@ AUTH0_AUDIENCE="https://your-api-identifier"
 AUTH0_ISSUER="https://your-tenant.us.auth0.com/"
 
 # ============================================
-# Flight Tracking API (Optional)
+# Optional Services
 # ============================================
-AVIATIONSTACK_API_KEY="your-aviationstack-api-key"
+# Leave empty or remove to disable the feature.
+# The app auto-detects which features are available.
+
+# Flight tracking API (https://aviationstack.com/)
+AVIATIONSTACK_API_KEY=
+
+# AI Copilot (https://console.anthropic.com/)
+ANTHROPIC_API_KEY=
+
+# Signal webhook authentication (recommended in production)
+SIGNAL_WEBHOOK_SECRET=