Initial commit: WYSIWYG Markdown Editor - Go backend + React/TypeScript frontend with Tailwind CSS

Backend:
- Cobra CLI with --data-dir, --port, --host flags
- Gin HTTP server with REST API for markdown CRUD operations
- File storage on disk (.md files only)
- Comprehensive logrus logging
- Backend tests with CRUD round-trip verification

Frontend:
- React 18 + TypeScript + Tailwind CSS
- Markdown editor with live GFM preview (react-markdown + remark-gfm)
- File management UI (list, create, open, save, delete)
- Theme switcher with Dark/Light/System modes
- Responsive design
- Frontend tests with vitest

Testing:
- All backend tests pass (go test ./...)
- All frontend tests pass (npm test)

internal/server/server.go

@@ -0,0 +1,115 @@
+package server
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"os"
+	"path/filepath"
+
+	"github.com/sirupsen/logrus"
+	"markdown-editor/internal/storage"
+	"markdown-editor/internal/api"
+	"markdown-editor/internal/logger"
+
+	"github.com/gin-gonic/gin"
+)
+
+type Server struct {
+	dataDir string
+	port    int
+	host    string
+	storage *storage.Storage
+	api     *api.API
+	router  *gin.Engine
+	httpSrv *http.Server
+	log     *logrus.Logger
+}
+
+func NewServer(dataDir string, port int, host string) *Server {
+	log := logger.GetLogger()
+
+	s := &Server{
+		dataDir: dataDir,
+		port:    port,
+		host:    host,
+		log:     log,
+	}
+
+	var err error
+	s.storage, err = storage.NewStorage(dataDir)
+	if err != nil {
+		log.Fatalf("Failed to initialize storage: %v", err)
+	}
+
+	s.api = api.NewAPI(s.storage)
+
+	// Initialize Gin router
+	s.router = gin.New()
+	s.router.Use(gin.Logger())
+	s.router.Use(gin.Recovery())
+
+	return s
+}
+
+func (s *Server) Start() error {
+	s.log.Info("Starting HTTP server")
+
+	// Register API routes
+	s.api.RegisterRoutes(s.router)
+
+	// Serve static files from frontend build
+	s.serveStaticAssets()
+
+	// Build the URL
+	url := fmt.Sprintf("%s:%d", s.host, s.port)
+	s.log.Infof("Server listening on %s", url)
+
+	s.httpSrv = &http.Server{
+		Addr:    url,
+		Handler: s.router,
+	}
+
+	return s.httpSrv.ListenAndServe()
+}
+
+func (s *Server) serveStaticAssets() {
+	// Try to serve from multiple possible locations
+	possiblePaths := []string{
+		"./frontend/dist",
+		"frontend/dist",
+	}
+
+	var assetPath string
+	for _, path := range possiblePaths {
+		if _, err := os.Stat(path); err == nil {
+			assetPath = path
+			break
+		}
+	}
+
+	if assetPath == "" {
+		s.log.Warn("Frontend build not found, serving API only")
+		return
+	}
+
+	s.log.Infof("Serving static assets from: %s", assetPath)
+
+	// Serve files from the dist directory
+	s.router.Static("/", assetPath)
+	s.router.Static("/assets", filepath.Join(assetPath, "assets"))
+}
+
+func (s *Server) Shutdown(ctx context.Context) error {
+	s.log.Info("Shutting down HTTP server")
+
+	// Clean up storage
+	if s.storage != nil {
+		s.storage = nil
+	}
+
+	if s.httpSrv != nil {
+		return s.httpSrv.Shutdown(ctx)
+	}
+	return nil
+}