- Created javascript-repl.ts tool with SandboxedIframe for code execution
- Integrated into ChatPanel replacing calculate and getCurrentTime tools
- REPL provides full browser API access with external library support
- Auto-registers renderer for tool output display
- Uses srcdoc instead of sandbox.html (no CSP restrictions in web apps)
Fixed loadContent() and execute() to set srcdoc at the correct time:
- loadContent(): Now sets srcdoc after creating iframe (was missing entirely)
- execute(): Now sets srcdoc after setting up message listeners and creating iframe (was setting before iframe existed)
This prevents missing postMessage events from the sandboxed iframe.
