refactor(scroll): clean up debug overlay and pass anchor by param

Removes the temporary on-screen scroll diagnosis panel and the global
window.__scrollAtClick stash. The anchor scrollTop is now captured
synchronously at addStackedNote entry and threaded through
scrollToFocusedNote and scrollToNoteElement to scrollToElement, so no
state survives across calls — nothing to reset on repo or page change.

src/App.vue

@@ -13,7 +13,6 @@ const { isATProtoReady } = useATProtoLogin()
 
     <new-version />
   </div>
-  <pre id="scroll-debug"></pre>
 </template>
 
 <style lang="scss">
@@ -46,23 +45,4 @@ const { isATProtoReady } = useATProtoLogin()
 ::view-transition-new(remanso-logo) {
   object-fit: contain;
 }
-
-#scroll-debug {
-  position: fixed;
-  bottom: 0;
-  left: 0;
-  z-index: 9999;
-  margin: 0;
-  padding: 4px 6px;
-  background: rgba(0, 0, 0, 0.75);
-  color: #fff;
-  font: 10px/1.3 ui-monospace, monospace;
-  white-space: pre;
-  pointer-events: none;
-  max-width: 100vw;
-}
-
-#scroll-debug:empty {
-  display: none;
-}
 </style>