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/WidgetPhotos.vue

@@ -26,7 +26,7 @@ import { onUnmounted, ref } from 'vue';
 import * as Misskey from 'misskey-js';
 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 { useStream } from '@/stream.js';
 import { getStaticImageUrl } from '@/utility/media-proxy.js';
 import { misskeyApi } from '@/utility/misskey-api.js';
@@ -38,14 +38,14 @@ const name = 'photos';
 
 const widgetPropsDef = {
 	showHeader: {
-		type: 'boolean' as const,
+		type: 'boolean',
 		default: true,
 	},
 	transparent: {
-		type: 'boolean' as const,
+		type: 'boolean',
 		default: false,
 	},
-};
+} satisfies FormWithDefault;
 
 type WidgetProps = GetFormResultType<typeof widgetPropsDef>;