Fix: Prayer Request Multiple prays

[TenzDelek]

fix #856

[greptile-apps]

Confidence Score: 4/5

[Medium risk] Prayer request feature adds multi-prayer support and UI changes.

The PR is not ready to merge because sign-out can still leave accepted prayer taps unsent.

Findings

1.  Sign-out loses queued prayers ▶

Fix with agent prompt

### Issue 1
lib/features/group_chat/presentation/providers/prayer_requests_providers.dart:195-196
If someone closes the prayer sheet and signs out before `_drain` sends their queued taps, the call runs after their credentials are cleared. It fails, and `_drain` drops prayers the button already showed as added. Keep the queued prayers tied to that account, or send them before sign-out.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (5) · Last reviewed commit: "fix last"}

[TenzDelek]

@greptileai review