Remove Gorush, use direct APNs/FCM, fix worker queries

- Remove Gorush push server dependency (now using direct APNs/FCM)
- Update docker-compose.yml to remove gorush service
- Update config.go to remove GORUSH_URL
- Fix worker queries:
  - Use auth_user instead of user_user table
  - Use completed_at instead of completion_date column
- Add NotificationService to worker handler for actionable notifications
- Add docs/PUSH_NOTIFICATIONS.md with architecture documentation
- Update README.md, DOKKU_SETUP.md, and dev.sh

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

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

README.md

@@ -1,12 +1,12 @@
 # Casera API (Go)
 
-Go implementation of the Casera property management API, built with Gin, GORM, Gorush, and GoAdmin.
+Go implementation of the Casera property management API, built with Gin, GORM, and GoAdmin.
 
 ## Tech Stack
 
 - **HTTP Framework**: [Gin](https://github.com/gin-gonic/gin)
 - **ORM**: [GORM](https://gorm.io/) with PostgreSQL
-- **Push Notifications**: [Gorush](https://github.com/appleboy/gorush) (embedded)
+- **Push Notifications**: Direct APNs (via [apns2](https://github.com/sideshow/apns2)) + FCM HTTP API
 - **Admin Panel**: [GoAdmin](https://github.com/GoAdminGroup/go-admin)
 - **Background Jobs**: [Asynq](https://github.com/hibiken/asynq)
 - **Caching**: Redis
@@ -66,7 +66,7 @@ myCribAPI-go/
 │   ├── middleware/          # Gin middleware
 │   ├── dto/                 # Request/Response DTOs
 │   ├── router/              # Route setup
-│   ├── push/                # Gorush integration
+│   ├── push/                # APNs/FCM push notifications
 │   ├── worker/              # Asynq jobs
 │   └── admin/               # GoAdmin tables
 ├── pkg/