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/WidgetRss.vue

@@ -26,7 +26,7 @@ import { url as base } from '@@/js/config.js';
 import { useInterval } from '@@/js/use-interval.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 MkContainer from '@/components/MkContainer.vue';
 import { i18n } from '@/i18n.js';
 
@@ -34,22 +34,22 @@ const name = 'rss';
 
 const widgetPropsDef = {
 	url: {
-		type: 'string' as const,
+		type: 'string',
 		default: 'http://feeds.afpbb.com/rss/afpbb/afpbbnews',
 	},
 	refreshIntervalSec: {
-		type: 'number' as const,
+		type: 'number',
 		default: 60,
 	},
 	maxEntries: {
-		type: 'number' as const,
+		type: 'number',
 		default: 15,
 	},
 	showHeader: {
-		type: 'boolean' as const,
+		type: 'boolean',
 		default: true,
 	},
-};
+} satisfies FormWithDefault;
 
 type WidgetProps = GetFormResultType<typeof widgetPropsDef>;