fix: resolve Windows compilation errors and warnings

- Add Manager trait import for windows_startup_cmd.rs
- Add explicit type annotations for PathBuf in windows_startup_cmd.rs
- Fix unused import warning in screenshot_capture_service.rs
- Prefix unused variables with underscore in runner.rs and aster_agent_cmd.rs
- Update package.json with Node.js engine requirement

package.json

@@ -3,6 +3,9 @@
   "private": true,
   "version": "0.83.0",
   "type": "module",
+  "engines": {
+    "node": ">=22.0.0"
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/aiclientproxy/proxycast.git"