* fix(chat): preserve chronological message order during history pagination
The baseDisplayMessages dedup loop iterated from tail to head (newest
to oldest), keeping the newer occurrence of each message ID. During
history pagination (prepend mode), the server returns older messages
that may overlap with the current view at the boundary. The tail-first
iteration discarded the older (prepended) duplicate in favor of the
newer (existing) one, breaking chronological ordering.
Change the loop to iterate head to tail (oldest to newest) so the
first occurrence of each time-sortable message ID is preserved. Remove
the now-unnecessary .reverse() call.
Fixes#2088
* test(chat): add dedup logic coverage for baseDisplayMessages
Covers message ID deduplication in baseDisplayMessages useMemo:
- First-occurrence preservation during dedup
- Input order maintenance
- Empty input, single-element, all-same-ID edge cases
- History pagination prepend scenario with overlapping IDs
---------
Co-authored-by: bashrusakh <bashrusakh@users.noreply.github.com>
