Fix scroll-to-factcheck: use scroll event lock during rendering

The double-rAF callbacks from resizeTileToContent fire after the
initial scrollTop=0 reset. Add a scroll event listener that forces
scrollTop=0 during the entire rendering phase, then remove it after
3 animation frames (covering all double-rAF resize callbacks).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/static/js/app.js

@@ -636,15 +636,18 @@ const App = {
         if (inc) this._announceForSR('Lage ausgewählt: ' + inc.title);
         this.renderSidebar();
 
-        var mc = document.getElementById("main-content");
+        var mc = document.getElementById(main-content);
         mc.scrollTop = 0;
 
         document.getElementById('empty-state').style.display = 'none';
         document.getElementById('incident-view').style.display = 'flex';
 
-        // GridStack-Animation temporaer deaktivieren um Scroll-Sprung zu verhindern
+        // GridStack-Animation deaktivieren und Scroll komplett sperren
+        // bis alle Tile-Resize-Operationen (doppeltes rAF) abgeschlossen sind
         var gridEl = document.querySelector('.grid-stack');
         if (gridEl) gridEl.classList.remove('grid-stack-animate');
+        var scrollLock = function() { mc.scrollTop = 0; };
+        mc.addEventListener('scroll', scrollLock);
 
         // gridstack-Layout initialisieren (einmalig)
         if (typeof LayoutManager !== 'undefined') LayoutManager.init();
@@ -660,11 +663,16 @@ const App = {
 
         await this.loadIncidentDetail(id);
 
-        // Zum Header scrollen und Animation wieder aktivieren
+        // Scroll-Sperre nach 3 Frames aufheben (nach allen doppelten rAF-Callbacks)
         mc.scrollTop = 0;
         requestAnimationFrame(() => {
-            mc.scrollTop = 0;
-            if (gridEl) gridEl.classList.add('grid-stack-animate');
+            requestAnimationFrame(() => {
+                requestAnimationFrame(() => {
+                    mc.scrollTop = 0;
+                    mc.removeEventListener('scroll', scrollLock);
+                    if (gridEl) gridEl.classList.add('grid-stack-animate');
+                });
+            });
         });