Scroll into filtered feed/category on page load (#8281)

Previously if you were to go to for example *Subscription management* and filter a feed, the feed wouldn't be visible in a sidebar with lots of feeds, since you'd have to scroll to it first. Now, this is no longer the case.
Note that if the navigation comes from the sidebar itself, the original behavior remains. (scroll into previous `scrollTop` value of sidebar)
Also improves experience of using shift+j/k (see https://github.com/FreshRSS/FreshRSS/pull/8057)

p/scripts/main.js

@@ -1018,9 +1018,6 @@ function init_column_categories() {
 		return;
 	}
 
-	// Restore sidebar scroll position
-	document.getElementById('sidebar').scrollTop = +sessionStorage.getItem('FreshRSS_sidebar_scrollTop');
-
 	// Restore open categories
 	if (context.display_categories === 'remember') {
 		const open_categories = JSON.parse(localStorage.getItem('FreshRSS_open_categories') || '{}');
@@ -1029,6 +1026,23 @@ function init_column_categories() {
 		});
 	}
 
+	const sidebar_scrollTop = sessionStorage.getItem('FreshRSS_sidebar_scrollTop');
+	if (sidebar_scrollTop) {
+		// Restore sidebar scroll position (navigated from sidebar)
+		document.querySelector('ul#sidebar').scrollTop = +sidebar_scrollTop;
+		sessionStorage.removeItem('FreshRSS_sidebar_scrollTop');
+	} else {
+		// Scroll into filtered feed/category on sidebar (navigated from anywhere)
+		const params = new URLSearchParams(location.search);
+		const get = params.get('get');
+		if (params.has('get') && (get.startsWith('f_') || get.startsWith('c_'))) {
+			const selectedEl = document.getElementById(get);
+			if (selectedEl) {
+				selectedEl.scrollIntoView({ block: get.startsWith('f_') ? 'center' : 'start' });
+			}
+		}
+	}
+
 	document.getElementById('aside_feed').onclick = function (ev) {
 		let a = ev.target.closest('.tree-folder > .tree-folder-title > button.dropdown-toggle');
 		if (a) {
@@ -2237,12 +2251,23 @@ function init_normal() {
 	init_actualize();
 	faviconNbUnread();
 
-	document.addEventListener("visibilitychange", () => {
-		if (document.visibilityState === "hidden") {
-			const sidebar = document.getElementById('sidebar');
-			if (sidebar) {	// Save sidebar scroll position
+	const sidebar = document.querySelector('ul#sidebar');
+	if (sidebar) {
+		sidebar.addEventListener('click', (e) => {
+			if (!e.isTrusted) {
+				// Event was likely called via a keyboard shortcut shift+j/k using click()
+				return;
+			}
+			const target = e.target.closest('a.item-title, a.tree-folder-title');
+			if (target) {
+				// A page navigation should occur now, save the sidebar scroll position
 				sessionStorage.setItem('FreshRSS_sidebar_scrollTop', sidebar.scrollTop);
 			}
+		});
+	}
+
+	document.addEventListener("visibilitychange", () => {
+		if (document.visibilityState === "hidden") {
 			if (mark_read_queue && mark_read_queue.length > 0) {
 				clearTimeout(send_mark_read_queue_timeout);
 				send_mark_queue_tick(null);