- Skip older-history loads silently while the connection is down:
the trigger previously failed with "not connected", popped the
global alert over the timeline and froze scrolling until dismissed.
- Accept fast reply-swipe flicks whose end state is clearly leftward
even without an intermediate horizontal lock, while scroll-owned
touches still never activate the swipe.
- Add a seeded-chat UI test mode (launch argument), accessibility
identifiers and a LumaUITests target with timeline scroll and reply
swipe tests; guard the fix in verify.sh.
