feat: implement Anthropic native PDF support with document preservation

- Add comprehensive debug logging throughout PDF processing pipeline
- Refactor attachment processing to separate image and document handling
- Create distinct addImageURLs(), addDocuments(), and processAttachments() methods
- Fix critical bugs in stream handling and parameter passing
- Add streamToBuffer utility for proper stream-to-buffer conversion
- Remove api/agents submodule from repository

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

client/src/components/Chat/Messages/Content/ProgressCircle.tsx

@@ -15,7 +15,7 @@ export default function ProgressCircle({
       className="absolute left-1/2 top-1/2 h-[23px] w-[23px] -translate-x-1/2 -translate-y-1/2 text-brand-purple"
     >
       <circle
-        className="origin-[50%_50%] -rotate-90 stroke-brand-purple/25 dark:stroke-brand-purple/50"
+        className="stroke-brand-purple/25 dark:stroke-brand-purple/50 origin-[50%_50%] -rotate-90"
         strokeWidth="7.826086956521739"
         fill="transparent"
         r={radius}