docs: update AGENTS.md with webui build guidance

- Add npm run build-static command documentation
- Include webui development workflow instructions
- Document build system integration with CMake
- Add troubleshooting guidance for common issues

AGENTS.md

@@ -8,6 +8,7 @@ This is a C++ REST API server that wraps the stable-diffusion.cpp library, provi
 
 
 Always use todo tools to track the status
+
 ## Build Commands
 
 ### Main Build Process