feat: update Go server to serve static files

cmd/api/main.go

@@ -68,6 +68,18 @@ func main() {
 		}
 	})
 
+	// Serve static files from static/ directory
+	http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("static"))))
+
+	// Serve frontend
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/" || r.URL.Path == "/index.html" {
+			http.ServeFile(w, r, "static/index.html")
+			return
+		}
+		http.NotFound(w, r)
+	})
+
 	log.Println("Trip Planner API starting on :8080")
 	log.Fatal(http.ListenAndServe(":8080", nil))
 }