fix: apply the BrandingName setting to the masthead and page title

The brandingName admin setting was saved but never used — layout/login/register
hardcoded "Bounty Board". render() now passes the configured brand into every
page, and the top-nav masthead, <title>, and login/register headers use it.
(The "Bounty Board" board-feature labels are left as-is.)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

internal/http/web.go

@@ -23,6 +23,7 @@ type pageData struct {
 	User         *domain.User
 	DefaultTheme string
 	NavLayout    string
+	Brand        string
 	Narrow       bool
 	OIDCEnabled  bool
 	Error        string
@@ -88,6 +89,12 @@ func (s *Server) render(w http.ResponseWriter, r *http.Request, page string, dat
 			data.NavLayout = "top"
 		}
 	}
+	if data.Brand == "" {
+		data.Brand = "Bounty Board"
+		if st, err := s.store.GetSettings(r.Context()); err == nil && st.BrandingName != "" {
+			data.Brand = st.BrandingName
+		}
+	}
 	w.Header().Set("Content-Type", "text/html; charset=utf-8")
 	if err := t.ExecuteTemplate(w, "layout", data); err != nil {
 		s.log.Error("execute template", "page", page, "err", err)