Fix MIME type handling for static files

- Add custom static file handler with proper Content-Type headers
- Fix CSS and JavaScript files being served as text/plain
- Add favicon handler to prevent 404 errors

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

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

internal/server/server.go

@@ -5,7 +5,9 @@ import (
 	"embed"
 	"encoding/json"
 	"log"
+	"mime"
 	"net/http"
+	"path"
 	"sync"
 
 	"github.com/gorilla/mux"
@@ -54,6 +56,7 @@ func New(cfg *config.Config, staticFiles embed.FS, ctx context.Context) http.Han
 	router := mux.NewRouter()
 
 	router.HandleFunc("/", s.serveIndex).Methods("GET")
+	router.HandleFunc("/favicon.ico", s.serveFavicon).Methods("GET")
 	router.HandleFunc("/ws", s.handleWebSocket).Methods("GET")
 	
 	apiRouter := router.PathPrefix("/api").Subrouter()
@@ -61,7 +64,7 @@ func New(cfg *config.Config, staticFiles embed.FS, ctx context.Context) http.Han
 	apiRouter.HandleFunc("/stats", s.getStats).Methods("GET")
 	apiRouter.HandleFunc("/config", s.getConfig).Methods("GET")
 
-	router.PathPrefix("/static/").Handler(http.StripPrefix("/static/", http.FileServer(http.FS(s.staticFiles))))
+	router.PathPrefix("/static/").Handler(http.StripPrefix("/static/", s.staticFileHandler()))
 
 	return s.enableCORS(router)
 }
@@ -77,6 +80,11 @@ func (s *Server) serveIndex(w http.ResponseWriter, r *http.Request) {
 	w.Write(data)
 }
 
+func (s *Server) serveFavicon(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "image/x-icon")
+	w.WriteHeader(http.StatusNotFound)
+}
+
 func (s *Server) getAircraft(w http.ResponseWriter, r *http.Request) {
 	data := s.dump1090.GetAircraftData()
 	
@@ -194,6 +202,38 @@ 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
+		
+		data, err := s.staticFiles.ReadFile(filePath)
+		if err != nil {
+			http.NotFound(w, r)
+			return
+		}
+
+		ext := path.Ext(filePath)
+		contentType := mime.TypeByExtension(ext)
+		if contentType == "" {
+			switch ext {
+			case ".css":
+				contentType = "text/css"
+			case ".js":
+				contentType = "application/javascript"
+			case ".svg":
+				contentType = "image/svg+xml"
+			case ".html":
+				contentType = "text/html"
+			default:
+				contentType = "application/octet-stream"
+			}
+		}
+
+		w.Header().Set("Content-Type", contentType)
+		w.Write(data)
+	})
+}
+
 func (s *Server) enableCORS(handler http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Access-Control-Allow-Origin", "*")