chore: Flutter mobile app, CI, and dev tooling

- mobile/: Flutter/Dart merchant mobile app skeleton
- .github/: GitHub Actions CI workflows
- .dockerignore: exclude host node_modules from build context
- .cursorrules: Cursor IDE project rules
- .claude/: Claude Code project settings and launch config

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

mobile/meezi_pos/pubspec.yaml

@@ -0,0 +1,26 @@
+name: meezi_pos
+description: Meezi tablet POS (Riverpod, Drift, offline sync)
+publish_to: "none"
+version: 0.1.0+1
+
+environment:
+  sdk: ">=3.2.0 <4.0.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+  flutter_localizations:
+    sdk: flutter
+  flutter_riverpod: ^2.6.1
+  go_router: ^14.6.2
+  dio: ^5.7.0
+  shamsi_date: ^1.0.4
+  intl: any
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+  flutter_lints: ^5.0.0
+
+flutter:
+  uses-material-design: true