feat: generic camera stream support for http snapshot and rtsp

src/slic3r/Utils/SnapmakerPrinterAgent.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "IPrinterAgent.hpp"
 #include "MoonrakerPrinterAgent.hpp"
 
 #include <atomic>
@@ -21,6 +22,8 @@ public:
     FilamentSyncMode get_filament_sync_mode() const override;
     int connect_printer(std::string dev_id, std::string dev_ip, std::string username, std::string password, bool use_ssl) override;
     int command_start_camera(std::string dev_id) override;
+    CameraStreamMode get_camera_stream_mode() const override { return CameraStreamMode::http_snapshot; }
+    std::string get_camera_url() const override { return device_info.base_url + "/server/files/camera/monitor.jpg"; }
 
 private:
     // Combine filament_type + filament_sub_type into a unified type string