feat: icons moved to repo-managed PNG files

- Convert all brand icons (aliyun/baidu/quark/115/tianyi/123pan/uc/xunlei/pikpak) to 64x64 PNG

 - CLOUD_ICONS now references /icons/xxx.png instead of data URI

 - Backend cloud-types.service.ts synchronized

 - Added magnet/ed2k/others placeholder icons

 - .gitignore allows public/icons/

.gitignore

@@ -14,6 +14,7 @@ deploy.sh
 backup.sh
 check.sh
 icons/
+!/packages/frontend/public/icons/
 scripts/
 Dockerfile
 Dockerfile.bak