## Summary
- keep transparent channel-list gaps in Flutter's gesture arena
- allow a new drag to interrupt active ballistic scrolling immediately
- add a behavioral fling-and-counter-drag regression test
## Scope audit
- audited mobile list and scroll constructors across `mobile/lib`
- channels is the only app scrollable overriding `hitTestBehavior`
- all other lists retain Flutter's default opaque hit testing and do not
share this defect
## Verification
- regression test fails before the production change: ballistic offset
continues from `271.17` to `345.56`
- focused interruption regression passes with the fix
- profile/community control test passes
- pre-commit: Dart formatting and Flutter analyzer pass
- pre-push: complete mobile suite passes, 1323 tests
- simulator: immediate counter-drag from the transparent gutter
interrupts deceleration
Simulator evidence:
`/Users/wesb/.buzz/.scratch/mobile-scroll-videos/interruption-verified.mp4`
Signed-off-by: Wes <wesbillman@users.noreply.github.com>
Co-authored-by: Carl <c7ebe626f000404285d3686e1dc74cc07cc60a9754a150041ba132e14bd3e2ec@buzz.block.builderlab.xyz>
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