chore(editor): update loading css vars (#12557)

Related to: [BS-3559](https://linear.app/affine-design/issue/BS-3559/ui-%E5%9B%BE%E7%89%87-loading-%E5%8F%98%E9%87%8F%E6%9B%B4%E6%96%B0)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **Style**
  - Improved the appearance of image loading indicators by updating background and ring colors for a more consistent visual experience.

- **New Features**
  - Added customization options for the loading icon's ring color.

- **Chores**
  - Updated the "@toeverything/theme" dependency to version ^1.1.15 across multiple packages for improved consistency and compatibility.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/admin/package.json

@@ -39,7 +39,7 @@
     "@sentry/react": "^9.2.0",
     "@tanstack/react-table": "^8.20.5",
     "@toeverything/infra": "workspace:*",
-    "@toeverything/theme": "^1.1.14",
+    "@toeverything/theme": "^1.1.15",
     "cmdk": "^1.0.4",
     "embla-carousel-react": "^8.5.1",
     "input-otp": "^1.4.1",