Fix static file serving with correct MIME types

- Correct embed file path construction in staticFileHandler
- Static files now served with proper Content-Type headers
- CSS files: text/css, JS files: text/javascript, SVG files: image/svg+xml
- Resolves browser MIME type mismatch errors

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

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

internal/server/server.go

@@ -204,7 +204,7 @@ func (s *Server) broadcastToWebSocketClients(message WebSocketMessage) {
 
 func (s *Server) staticFileHandler() http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		filePath := "static" + r.URL.Path
+		filePath := "static/" + r.URL.Path
 		
 		data, err := s.staticFiles.ReadFile(filePath)
 		if err != nil {