refactor(frontend): Formまわりの型強化 (#16260)

* refactor(frontend): Formまわりの型強化

* fix

* avoid non-null assertion and add null check for safety

* refactor

* avoid non-null assertion and add null check for safety

* Update clip.vue

---------

Co-authored-by: syuilo <4439005+syuilo@users.noreply.github.com>

packages/frontend/src/widgets/WidgetCalendar.vue

@@ -41,7 +41,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 import { ref } from 'vue';
 import { useWidgetPropsManager } from './widget.js';
 import type { WidgetComponentEmits, WidgetComponentExpose, WidgetComponentProps } from './widget.js';
-import type { GetFormResultType } from '@/utility/form.js';
+import type { FormWithDefault, GetFormResultType } from '@/utility/form.js';
 import { i18n } from '@/i18n.js';
 import { useInterval } from '@@/js/use-interval.js';
 
@@ -49,10 +49,10 @@ const name = 'calendar';
 
 const widgetPropsDef = {
 	transparent: {
-		type: 'boolean' as const,
+		type: 'boolean',
 		default: false,
 	},
-};
+} satisfies FormWithDefault;
 
 type WidgetProps = GetFormResultType<typeof widgetPropsDef>;