f92a0b8596
Feishu already had text batching with a static 0.6s delay. This adds adaptive delay: waits 2.0s when a chunk is near the ~4096-char split point since a continuation is almost certain. Tracks _last_chunk_len on each queued event to determine the delay. Configurable via HERMES_FEISHU_TEXT_BATCH_SPLIT_DELAY_SECONDS (default 2.0). Ref #6892