style: update various code copy button and toc styles

- Removed the old copy-action SVG icon and replaced it with a new copy-button SVG icon.
- Added a new copy-success SVG icon for visual feedback on copy actions.
- Updated Waline component comments for clarity and improved code readability.
- Enhanced BackButton component with fallback navigation to homepage.
- Improved CodeCopyButton component by refining icon handling and timeout management.
- Adjusted GithubCard component's intersection observer root margin for better visibility.
- Updated GsapAnimation component variable names for consistency and clarity.
- Removed unnecessary styles from PhotoSwipe component.
- Modified TOC component styles for better spacing and layout.
- Updated multiple theme guide markdown files to correct image hosting URL comments.
- Cleaned up extend.css by removing commented-out styles and organizing code.
- Added PhotoSwipe background color and KaTeX overflow fixes to global.css.
- Enhanced markdown.css with video styling for better responsiveness.
- Improved transition.css comments for better understanding of GSAP animation states.

package.json

@@ -22,7 +22,7 @@
     "astro-og-canvas": "^0.7.0",
     "astro-robots-txt": "^1.0.0",
     "canvaskit-wasm": "^0.40.0",
-    "feed": "^5.0.1",
+    "feed": "^5.1.0",
     "gsap": "^3.13.0",
     "katex": "^0.16.22",
     "markdown-it": "^14.1.0",