feat: add Digital Ocean App Platform deployment

- Create App Platform deployment spec (.do/app.yaml)
- Add comprehensive APP_PLATFORM_DEPLOYMENT.md guide
- Configure Docker Hub as container registry
- Set up managed PostgreSQL database
- Configure auto-SSL and custom domain support
- Total cost: ~$17/month (vs $24+ for droplets)

Images available on Docker Hub:
- t72chevy/vip-coordinator-backend:latest
- t72chevy/vip-coordinator-frontend:latest

Images also available on Gitea:
- gitea.madeamess.online/kyle/vip-coordinator/backend:latest
- gitea.madeamess.online/kyle/vip-coordinator/frontend:latest

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

.do/app.yaml

@@ -0,0 +1,67 @@
+# Digital Ocean App Platform Spec
+# Deploy VIP Coordinator from Docker Hub
+name: vip-coordinator
+region: nyc
+
+# Managed Database (PostgreSQL)
+databases:
+  - name: vip-db
+    engine: PG
+    version: "16"
+    production: false  # Dev tier ($7/month) - set true for prod ($15/month)
+
+services:
+  # Backend API Service
+  - name: backend
+    image:
+      registry_type: DOCKER_HUB
+      registry: t72chevy
+      repository: vip-coordinator-backend
+      tag: latest
+      # For private repos, credentials configured separately
+    instance_count: 1
+    instance_size_slug: basic-xxs  # $5/month - smallest
+    http_port: 3000
+    health_check:
+      http_path: /api/v1/health
+      initial_delay_seconds: 40
+    envs:
+      - key: NODE_ENV
+        value: production
+      - key: DATABASE_URL
+        scope: RUN_TIME
+        value: ${vip-db.DATABASE_URL}
+      - key: REDIS_URL
+        value: ${redis.REDIS_URL}
+      - key: AUTH0_DOMAIN
+        value: dev-s855cy3bvjjbkljt.us.auth0.com
+      - key: AUTH0_AUDIENCE
+        value: https://vip-coordinator-api
+      - key: AUTH0_ISSUER
+        value: https://dev-s855cy3bvjjbkljt.us.auth0.com/
+    routes:
+      - path: /api
+
+  # Frontend Service
+  - name: frontend
+    image:
+      registry_type: DOCKER_HUB
+      registry: t72chevy
+      repository: vip-coordinator-frontend
+      tag: latest
+    instance_count: 1
+    instance_size_slug: basic-xxs  # $5/month
+    http_port: 80
+    routes:
+      - path: /
+
+# Redis Worker (using official image)
+jobs:
+  - name: redis
+    image:
+      registry_type: DOCKER_HUB
+      repository: redis
+      tag: "7-alpine"
+    instance_count: 1
+    instance_size_slug: basic-xxs  # $5/month
+    kind: PRE_DEPLOY