feat(input): accio MENU i assignacio de mando per path + name

Afegeix l'accio MENU a InputAction (obre el menu de servei des del mando,
equivalent a F12 al teclat) i els camps gamepad.button_start i
gamepad.button_menu al config per jugador. Tambe afegeix gamepad_path
per distingir dos mandos del mateix model i prioritza path > name >
slot a applyPlayerNBindings via el nou resolvePlayerGamepad.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

source/core/config/engine_config.hpp

@@ -48,12 +48,15 @@ namespace Config {
         int button_right{SDL_GAMEPAD_BUTTON_DPAD_RIGHT};
         int button_thrust{SDL_GAMEPAD_BUTTON_WEST};  // X button
         int button_shoot{SDL_GAMEPAD_BUTTON_SOUTH};  // A button
+        int button_start{SDL_GAMEPAD_BUTTON_START};  // Start button
+        int button_menu{SDL_GAMEPAD_BUTTON_BACK};    // Select/Back -> obre menu servei
     };
 
     struct PlayerBindings {
         KeyboardBindings keyboard{};
         GamepadBindings gamepad{};
         std::string gamepad_name;  // Empty = auto-assign by index
+        std::string gamepad_path;  // Prioritari sobre name per distingir mateixos models
     };
 
     struct AudioConfig {