fix: fix local proxy settings and restart logic

- Added local proxy restart token management in Settings.
- Implemented logic to handle local proxy state on application quit.
- Updated ProxyServer to restart based on configuration changes.
- Enhanced API configuration updates to bump restart token when necessary.
- Improved UI components to reflect local proxy availability and state.
- Added new error handling and notifications for local proxy operations.

client/settings.h

@@ -256,6 +256,8 @@ public:
     void setLocalProxyPortUserDefined(bool userDefined);
     bool isLocalProxyHttpEnabled() const;
     void setLocalProxyHttpEnabled(bool enabled);
+    int localProxyRestartToken() const;
+    void bumpLocalProxyRestartToken();
 
 signals:
     void saveLogsChanged(bool enabled);