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>

.claude/launch.json

@@ -0,0 +1,11 @@
+{
+  "version": "0.0.1",
+  "configurations": [
+    {
+      "name": "Dr Sousan API",
+      "runtimeExecutable": "dotnet",
+      "runtimeArgs": ["run", "--project", "F:/Projects/DrSousan/DrSousan.Api", "--urls", "http://localhost:5000"],
+      "port": 5000
+    }
+  ]
+}