fix(frontend): RSSウィジェットでURLエンコードを二重に行っている問題を修正 (#15272)

* don't double-url-encode rss urls

`url.searchParams.set()` already encodes the values passed!

(this is a partial revert of 0472d43ee9,
the change in `statusbar-rss.vue` was correct)

* Update Changelog

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Co-authored-by: dakkar <dakkar@thenautilus.net>

packages/frontend/src/widgets/WidgetRssTicker.vue

@@ -99,7 +99,7 @@ const items = computed(() => {
 const fetching = ref(true);
 const fetchEndpoint = computed(() => {
 	const url = new URL('/api/fetch-rss', base);
-	url.searchParams.set('url', encodeURIComponent(widgetProps.url));
+	url.searchParams.set('url', widgetProps.url);
 	return url;
 });
 const intervalClear = ref<(() => void) | undefined>();