feat(12.1-01): declared bulk actions on admin lists

- pact.HasAdminBulkActions with AdminBulkAction, its input and result
- config_list.yaml bulkActions, compiled fail-loud, needs showCheckboxes
- POST .../{controller}/bulk/{action}: ids resolved and locked through the
  list scope in one transaction; partial selection is 409
- list schema offers declared actions per principal, with confirm text
- admin SPA bulk actions menu with confirm, busy state and failure toasts
- acme.roster fixture, tracer test, OpenAPI, TS types, dist, READMEs, docs

modules/cabana/extension.go

@@ -67,6 +67,11 @@ func compileExtension(pluginID string, cc *CompiledController, fsys fs.FS) error
 		return fmt.Errorf("cabana: admin controller %s/%s: %w", pluginID, id, err)
 	}
 	cc.Actions = actions
+	bulkActions, err := compileBulkActions(cc.Controller)
+	if err != nil {
+		return fmt.Errorf("cabana: admin controller %s/%s: %w", pluginID, id, err)
+	}
+	cc.BulkActions = bulkActions
 	if err := compileClientAssets(pluginID, cc, fsys); err != nil {
 		return err
 	}
@@ -276,3 +281,30 @@ func compileActions(ctl pact.AdminController) (map[string]pact.AdminAction, erro
 	}
 	return out, nil
 }
+
+// compileBulkActions collects a controller's registered bulk actions. They
+// have their own namespace next to the toolbar and widget actions: a name is
+// unique among the bulk actions, and create and delete stay reserved.
+func compileBulkActions(ctl pact.AdminController) (map[string]pact.AdminBulkAction, error) {
+	out := map[string]pact.AdminBulkAction{}
+	src, ok := ctl.(pact.HasAdminBulkActions)
+	if !ok || src == nil {
+		return out, nil
+	}
+	for _, action := range src.AdminBulkActions() {
+		if !identifier(action.Name) {
+			return nil, fmt.Errorf("bulk action name %q is not an identifier", action.Name)
+		}
+		if builtinToolbarActions[action.Name] {
+			return nil, fmt.Errorf("bulk action %s uses a reserved built-in name (create, delete)", action.Name)
+		}
+		if _, dup := out[action.Name]; dup {
+			return nil, fmt.Errorf("duplicate bulk action %s", action.Name)
+		}
+		if action.Run == nil {
+			return nil, fmt.Errorf("bulk action %s has no Run function", action.Name)
+		}
+		out[action.Name] = action
+	}
+	return out, nil
+}