Add Discord attachment reading and web search capabilities

- Discord channel now downloads and extracts text from attachments (text files, PDFs)
- Added WebSearchTool using DuckDuckGo for researcher and coder agents
- Improved WebFetchTool with User-Agent header and HTML-to-text stripping
- Added pypdf and duckduckgo-search dependencies

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -17,6 +17,8 @@ dependencies = [
     "httpx>=0.28.0",
     "loguru>=0.7.0",
     "json-repair>=0.30.0",
+    "duckduckgo-search>=7.0.0",
+    "pypdf>=5.0.0",
 ]
 
 [project.scripts]