feat(17-04): menu plugin admin with registry types, URL checks and tree reorder

- golem15.menu plugin, tables golem15_menu_menus and golem15_menu_menu_entries with the PHP columns plus a nullable url_pattern (D-02)
- MenuEntry BeforeSave ports PHP beforeSave: nest columns 0, menu from the parent, sort_order after the menu's last
- entry type dropdown: url, divider and the signpost registry types; reference depends on type through signpost.ReferenceOptions
- URL scheme allowlist (errors.url_scheme), target _self or _blank, menu and parent cycle checks
- menu filter, toolbar reorder/create/delete and config_reorder.yaml partitioned by menu
- navigation Menus with Menus and Menu entries, permission golem15.menu.manage_menu, en and pl phrasebooks
- TestMenuAdminSmoke

admin_navigation.go

@@ -0,0 +1,38 @@
+package menu
+
+import (
+	"git.golem15.com/golem15/sm-menu-plugin/controllers"
+	"git.golem15.com/golem15/summercms/modules/pact"
+)
+
+// Navigation is a top-level Menus item with the side items Menus and Menu
+// entries. PHP hung both screens on another plugin's side menu
+// (SiteManager), which is not ported; the port registers its own.
+func (*Plugin) Navigation() []pact.NavigationItem {
+	return []pact.NavigationItem{{
+		Code:        "menu",
+		Label:       "golem15.menu::lang.plugin.name",
+		Icon:        "list",
+		Permissions: []string{"golem15.menu.*"},
+		Order:       510,
+		Controller:  controllers.MenusControllerID,
+		SideMenu: []pact.NavigationItem{
+			{
+				Code:        "menus",
+				Label:       "golem15.menu::lang.models.menu.label_plural",
+				Icon:        "list",
+				Permissions: []string{controllers.PermissionManageMenu},
+				Controller:  controllers.MenusControllerID,
+			},
+			{
+				Code:        "menuentries",
+				Label:       "golem15.menu::lang.models.menuentry.label_plural",
+				Icon:        "list-ordered",
+				Permissions: []string{controllers.PermissionManageMenu},
+				Controller:  controllers.MenuEntriesControllerID,
+			},
+		},
+	}}
+}
+
+var _ pact.HasNavigation = (*Plugin)(nil)