feat(mobile): Add field app with date range navigation

- Add React Native Expo field app for mobile staff
- Use main /appointments/ endpoint with date range support
- Add X-Business-Subdomain header for tenant context
- Support day/week view navigation
- Remove WebSocket console logging from frontend
- Update AppointmentStatus type to include all backend statuses
- Add responsive status legend to scheduler header

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

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

mobile/field-app/.gitignore

@@ -0,0 +1,40 @@
+# Dependencies
+node_modules/
+
+# Expo
+.expo/
+dist/
+expo-env.d.ts
+
+# Native builds
+*.orig.*
+*.jks
+*.p8
+*.p12
+*.key
+*.mobileprovision
+*.orig.*
+web-build/
+ios/
+android/
+
+# Environment files
+.env
+.env.local
+.env.*.local
+
+# Editor
+.idea/
+.vscode/
+
+# OS
+.DS_Store
+*.pem
+
+# Debug
+npm-debug.*
+yarn-debug.*
+yarn-error.*
+
+# TypeScript
+*.tsbuildinfo