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/external/mtr/line_info.h

@@ -20,6 +20,10 @@ public:
     return _code.c_str();
   }
   // caller does not own the returned char pointers
+  const char* name() const {
+    return _name.c_str();
+  }
+  // caller does not own the returned char pointers
   const char* color() const {
     return _color.c_str();
   }
@@ -40,6 +44,7 @@ private:
   );
 
   std::string _code;
+  std::string _name;
   std::string _color;
   std::vector<StationInfo> _stations;
 };