fix: resolve circular import errors in TypeORM entities

- Use string-based @OneToMany relations in parent entities (wallet, ticket, service-plan)
  to break circular import chains that confused VS Code TS language server
- Add .vscode/settings.json to suppress Tailwind CSS @tailwindcss unknownAtRules warnings
- Reorder imports in child entities for consistency

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+  "css.customData": [],
+  "css.lint.unknownAtRules": "ignore",
+  "scss.lint.unknownAtRules": "ignore"
+}