fix(js): use Event() constructor instead of deprecated initEvent() (#9035)

`document.createEvent('Event')` followed by `Event.initEvent()` is
deprecated (https://developer.mozilla.org/en-US/docs/Web/API/Event/initEvent).
Replace the two remaining usages in `main.js` with the standard
`new Event(name, { bubbles, cancelable })` constructor, matching the
pattern already used in `extra.js`. The `bubbles` and `cancelable`
flags are kept identical (both `true`) so dispatch behaviour is
unchanged.

Fixes #5152

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

p/scripts/main.js

@@ -439,8 +439,7 @@ function mark_favorite(div) {
 	}));
 }
 
-const freshrssOpenArticleEvent = document.createEvent('Event');
-freshrssOpenArticleEvent.initEvent('freshrss:openArticle', true, true);
+const freshrssOpenArticleEvent = new Event('freshrss:openArticle', { bubbles: true, cancelable: true });
 
 function loadLazyImages(rootElement) {
 	rootElement.querySelectorAll('img[data-original], iframe[data-original], video[data-original], track[data-original]').forEach(function (el) {
@@ -2247,8 +2246,7 @@ function load_more_posts() {
 	req.send();
 }
 
-const freshrssLoadMoreEvent = document.createEvent('Event');
-freshrssLoadMoreEvent.initEvent('freshrss:load-more', true, true);
+const freshrssLoadMoreEvent = new Event('freshrss:load-more', { bubbles: true, cancelable: true });
 
 function init_load_more(box) {
 	box_load_more = box;