feat(web): display logs newest-first in web gateway UI (#369)

Reverse log display order so the most recent entries appear at the top,
removing the need to scroll to see latest activity.

Frontend: rename appendLogEntry to prependLogEntry, use prepend() for
DOM insertion, cap oldest entries from the bottom, and auto-scroll to
top. Backend: update recent_entries() doc comment to clarify the
oldest-first return order works correctly with the frontend's prepend.

Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>

src/channels/web/log_layer.rs

@@ -90,6 +90,9 @@ impl LogBroadcaster {
     }
 
     /// Snapshot of recent entries for replaying to a new subscriber.
+    ///
+    /// Returns entries oldest-first so that the frontend's `prepend()`
+    /// naturally places the newest entry at the top of the DOM.
     pub fn recent_entries(&self) -> Vec<LogEntry> {
         self.recent
             .lock()