Include show_in_channel thread replies in the channel query response

[andremion]

What

The channel query response (paginate_message_list) only returned messages with parent_id == nil, which drops thread replies sent also to the channel. The backend's channel message predicate is (parent_id IS NULL) OR (show_in_channel = true), so those replies belong in the response.

Why it matters

This surfaced as the flaky test_threadReplyIsRemovedEverywhere_whenParticipantRemovesItFromChannel on Android (AND-1303). The chain, reconstructed from the per-attempt artifacts of the 2026-07-13 nightly:

1. The WebSocket drops mid-test on a loaded CI emulator and the client reconnects.
2. As part of recovery, the client re-queries the channel.
3. The response omits the also-in-channel reply, so the client (correctly, given the data) removes it from state, wiping the deleted-message placeholder the test was asserting. The placeholder was visible in the UI for 110ms before the response arrived.

The client behaved correctly; the response was the lie. Without a mid-test reconnect there is no re-query, which is why the test only flakes under CI load.

Testing

Against a local instance: seeded a regular message, a thread reply with thread_and_channel=true, and a thread-only reply, then POST /channels/messaging/{id}/query:

• the also-in-channel reply is now in messages (the fix)
• the thread-only reply stays excluded (no regression)
• regular messages unaffected

[andremion]

Started e2e tests on this branch:

• Android
• iOS

[andremion]

e2e results against this branch:

• iOS: green across the board.
• Android: 4 of 6 API levels green. The two failures are pre-existing known flakes, unrelated to this fix: test_originalQuoteIsDeletedByParticipant_deletedMessageIsShown_InThread (the lost-event-during-reconnect issue, see AND-1303) and test_deliveryStatusShownForPreviousMessage_whenSystemMessageShown (an assert race fixed in e2e: Fix the flaky test races and re-enable the composer giphy test stream-chat-android#6570, not yet merged when this ran).

No failures in the channel-query domain on either platform.