Remove udev rules, add GNOME desktop entry & SVG icon, and support V4L2-only open on Linux

assets/insta360-link-controller.desktop

@@ -0,0 +1,14 @@
+[Desktop Entry]
+Version=1.0
+Type=Application
+Name=Insta360 Link Controller
+GenericName=Webcam Controller
+Comment=Hardware PTZ, AI tracking, image settings, and live preview controller for Insta360 Link webcams
+Exec=insta360-link-gui
+TryExec=insta360-link-gui
+Icon=insta360-link-controller
+Terminal=false
+Categories=AudioVideo;Video;Settings;HardwareSettings;
+Keywords=insta360;link;webcam;camera;ptz;gimbal;uvc;video;tracking;
+StartupNotify=true
+StartupWMClass=insta360-link-controller