feat(travel): Implement settings UI and web server for MTR route configuration

- Added MainUIHandler class to manage the main UI and polling for arrival data.
- Introduced SettingsUI class for displaying QR code and configuration options.
- Created SettingsUIHandler to manage settings UI lifecycle and web server interactions.
- Developed WebHandler to handle HTTP requests for MTR route settings, including adding and removing routes.
- Implemented web endpoints for fetching MTR lines, routes, and saving settings.
- Enhanced UI with responsive design for e-ink displays and added error handling for web interactions.

main/ui/apps/registry.cpp

@@ -1,9 +1,11 @@
 #include "ui/apps/registry.h"
 
 #include "ui/apps/iotdis/descriptor.h"
+#include "ui/apps/travel/descriptor.h"
 
 esp_err_t AppRegistry::init(void) {
   register_app(std::make_unique<IotDisDescriptor>());
+  register_app(std::make_unique<TravelDescriptor>());
 
   return ESP_OK;
 }