* fix(feishu): preserve block streaming text when final payload is missing
When Feishu card streaming receives block payloads without matching final/partial
callbacks, keep block text in stream state so onIdle close still publishes the
reply instead of an empty message. Add a regression test for block-only streaming.
Closes#30628
* Feishu: preserve streaming block fallback when final text is missing
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Co-authored-by: Tak Hoffman <[email protected]>
