fix: resolve all linting errors and dependency conflicts

- Update @types/node from ^18.15.0 to ^20.19.0 to resolve Vite 7.1.9 compatibility
- Remove unused imports in capacitor-platform-service-clean-integration.ts
- Replace non-null assertions with optional chaining for safer code
- Add explicit return types to all async functions and Vue component methods
- Replace console.log statements with comments for better code quality
- Fix unused parameters by prefixing with underscore
- Change Promise<any> to Promise<unknown> for better type safety
- All 31 linting errors resolved, build now passes cleanly

The plugin is now ready for integration with crowd-funder-for-time-pwa project
with clean TypeScript compilation and zero linting warnings.

package.json

@@ -75,7 +75,7 @@
     "@capacitor/ios": "^6.2.1",
     "@types/jest": "^29.5.0",
     "@types/jsdom": "^21.1.7",
-    "@types/node": "^18.15.0",
+    "@types/node": "^20.19.0",
     "@typescript-eslint/eslint-plugin": "^5.57.0",
     "@typescript-eslint/parser": "^5.57.0",
     "eslint": "^8.37.0",