Add minimal Web UI server

src/webui/server.go

@@ -0,0 +1,63 @@
+package webui
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/yggdrasil-network/yggdrasil-go/src/core"
+)
+
+type WebUIServer struct {
+	server *http.Server
+	log    core.Logger
+	listen string
+}
+
+func Server(listen string, log core.Logger) *WebUIServer {
+	return &WebUIServer{
+		listen: listen,
+		log:    log,
+	}
+}
+
+func (w *WebUIServer) Start() error {
+	mux := http.NewServeMux()
+
+	// Setup static files handler (implementation varies by build)
+	setupStaticHandler(mux)
+
+	// Serve any file by path (implementation varies by build)
+	mux.HandleFunc("/", func(rw http.ResponseWriter, r *http.Request) {
+		serveFile(rw, r, w.log)
+	})
+
+	// Health check endpoint
+	mux.HandleFunc("/health", func(rw http.ResponseWriter, r *http.Request) {
+		rw.WriteHeader(http.StatusOK)
+		rw.Write([]byte("OK"))
+	})
+
+	w.server = &http.Server{
+		Addr:           w.listen,
+		Handler:        mux,
+		ReadTimeout:    10 * time.Second,
+		WriteTimeout:   10 * time.Second,
+		MaxHeaderBytes: 1 << 20,
+	}
+
+	w.log.Infof("WebUI server starting on %s", w.listen)
+
+	if err := w.server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+		return fmt.Errorf("WebUI server failed: %v", err)
+	}
+
+	return nil
+}
+
+func (w *WebUIServer) Stop() error {
+	if w.server != nil {
+		return w.server.Close()
+	}
+	return nil
+}