Fix MIME type handling for static files

- Fixed static file path construction in staticFileHandler
- Removed duplicate 'static' prefix that was causing incorrect file paths
- Now properly serves CSS and JS files with correct MIME types
- Resolves browser security errors from MIME type mismatches

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

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

internal/server/server.go

@@ -410,7 +410,8 @@ func (s *Server) handleFavicon(w http.ResponseWriter, r *http.Request) {
 
 func (s *Server) staticFileHandler() http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		filePath := "static" + r.URL.Path
+		// Remove /static/ prefix from URL path to get the actual file path
+		filePath := "static" + r.URL.Path[len("/static"):]
 		
 		data, err := s.staticFiles.ReadFile(filePath)
 		if err != nil {