Embed UI in binary (fix 404 when web/ missing from WorkingDirectory). Document logs and troubleshooting.

Made-with: Cursor

internal/api/handler.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"nettopo-go/internal/scans"
+	"nettopo-go/internal/webui"
 )
 
 type Handler struct {
@@ -54,7 +55,7 @@ func NewHandler(store scans.Store, run *scans.Runner) *Handler {
 
 func (h *Handler) Routes() http.Handler {
 	mux := http.NewServeMux()
-	webFS := http.FileServer(http.Dir("web"))
+	webFS := http.FileServer(http.FS(webui.FS))
 	mux.Handle("GET /", webFS)
 	mux.Handle("GET /web/", http.StripPrefix("/web/", webFS))
 	mux.HandleFunc("GET /health", h.health)