Bug Description

Feishu/Lark inbound reply events can carry reply-tree context in root_id. Hermes currently resolves MessageEvent.reply_to_message_id from parent_id or upper_message_id only. If the SDK/event payload has root_id but no parent_id, Hermes does not fetch the replied-to/root message text, so the gateway never injects the [Replying to: ...] context for the agent.

This is separate from the Feishu topic outbound-routing issues tracked in #6969 / #17875: this report is only about inbound reply context (reply_to_message_id / reply_to_text).

Steps to Reproduce

1. Receive a Feishu im.message.receive_v1 event for a reply message where message.root_id is set but message.parent_id and message.upper_message_id are absent.
2. Let FeishuAdapter._process_inbound_message() normalize the event.
3. Inspect the resulting MessageEvent.

Expected Behavior

MessageEvent.reply_to_message_id should use the available reply root id, _fetch_message_text() should fetch the referenced message, and reply_to_text should be populated so the gateway can inject reply context.

Actual Behavior

reply_to_message_id is None, _fetch_message_text() is not called, and the agent receives the user's reply without explicit replied-to context.

Proposed Fix

Treat root_id as a fallback reply target after parent_id and upper_message_id, with regression coverage for root-id-only Feishu reply payloads.

Test Plan

• uv run pytest tests/gateway/test_feishu.py -q -o 'addopts='