Add minimal topology web UI and serve static files.

Provide browser-based topology viewer at root path and update technical spec checkboxes for completed UI milestone.

Made-with: Cursor

internal/api/handler.go

@@ -54,6 +54,9 @@ func NewHandler(store scans.Store, run *scans.Runner) *Handler {
 
 func (h *Handler) Routes() http.Handler {
 	mux := http.NewServeMux()
+	webFS := http.FileServer(http.Dir("web"))
+	mux.Handle("GET /", webFS)
+	mux.Handle("GET /web/", http.StripPrefix("/web/", webFS))
 	mux.HandleFunc("GET /health", h.health)
 	mux.HandleFunc("POST /api/scans", h.createScan)
 	mux.HandleFunc("GET /api/scans", h.listScans)
@@ -411,7 +414,9 @@ func (h *Handler) getScanTopology(w http.ResponseWriter, r *http.Request) {
 
 func withJSON(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		if strings.HasPrefix(r.URL.Path, "/api/") || r.URL.Path == "/health" {
+			w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		}
 		next.ServeHTTP(w, r)
 	})
 }