Update Helm chart to use unified app image (API + Frontend)

Changes:
- Replaced separate api and frontend deployments with single unified app deployment
- Updated values.yaml: Changed from api/frontend configs to single app config
- Renamed templates: api-deployment.yaml → app-deployment.yaml
- Removed frontend-deployment.yaml and frontend-service.yaml (no longer needed)
- Updated app image to warehouse13/app (multi-stage Docker build)
- Combined resource allocations: 384Mi memory, 350m CPU (up from separate totals)
- Updated all example values files (dev, production, air-gapped)
- Updated NOTES.txt to reflect single service on port 8000
- Updated ingress to route all traffic to single app service
- Added ARCHITECTURE.md documenting the unified container approach

Architecture:
The application now uses a multi-stage Docker build:
1. Stage 1: Builds Angular frontend with Node
2. Stage 2: Python FastAPI backend that serves static frontend from /static

Benefits:
- Simplified deployment (1 container instead of 2)
- Reduced resource usage (no separate nginx)
- Easier scaling (1 deployment to manage)
- Consistent versioning (frontend/backend always match)

Access pattern:
- http://localhost:8000     → Angular frontend
- http://localhost:8000/api → FastAPI REST API
- http://localhost:8000/docs → API documentation
- http://localhost:8000/health → Health check

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

helm/warehouse13/values-airgapped.yaml

@@ -50,37 +50,21 @@ minio:
       memory: "2Gi"
       cpu: "1000m"
 
-# API with custom registry
-api:
+# Application with custom registry (unified API + Frontend)
+app:
   enabled: true
   image:
-    repository: harbor.internal.example.com/warehouse13/api
+    repository: harbor.internal.example.com/warehouse13/app
     tag: v1.0.0
     pullPolicy: IfNotPresent
   replicas: 2
   resources:
     requests:
-      memory: "512Mi"
-      cpu: "500m"
+      memory: "768Mi"
+      cpu: "750m"
     limits:
-      memory: "1Gi"
-      cpu: "1000m"
-
-# Frontend with custom registry
-frontend:
-  enabled: true
-  image:
-    repository: harbor.internal.example.com/warehouse13/frontend
-    tag: v1.0.0
-    pullPolicy: IfNotPresent
-  replicas: 2
-  resources:
-    requests:
-      memory: "256Mi"
-      cpu: "250m"
-    limits:
-      memory: "512Mi"
-      cpu: "500m"
+      memory: "1536Mi"
+      cpu: "1500m"
 
 # Ingress disabled for air-gapped - use NodePort or port-forward
 ingress: