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

controllers/admin_registry.go

@@ -0,0 +1,21 @@
+// Package controllers holds the menu plugin's admin controllers.
+package controllers
+
+import (
+	"git.golem15.com/golem15/summercms/modules/backpack"
+	"git.golem15.com/golem15/summercms/modules/pact"
+)
+
+// PermissionManageMenu is the PHP permission golem15.menu.manage_menu; both
+// screens require it.
+const PermissionManageMenu = "golem15.menu.manage_menu"
+
+// AdminControllers is the plugin's admin controller list. app returns the
+// booted application; it is asked on every call, so a controller never keeps
+// a database handle or registry of its own.
+func AdminControllers(app func() *backpack.App) []pact.AdminController {
+	return []pact.AdminController{
+		menusAdminController{},
+		menuEntriesAdminController{app: app},
+	}
+}