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>

agents/coder.md

@@ -10,6 +10,7 @@ tools:
   - edit_file
   - list_dir
   - bash
+  - web_search
   - delegate
 ---
 

agents/researcher.md

@@ -5,6 +5,7 @@ model: nvidia_nim/deepseek-ai/deepseek-v3.1
 temperature: 0.5
 max_iterations: 20
 tools:
+  - web_search
   - web_fetch
   - read_file
   - list_dir