hermes - 💡(How to fix) Fix Wire LINE channel L into verified webhook ingress

What to build

Connect the new LINE Official Account / Messaging API channel named L to the personal butler bridge with verified webhook ingress. This is a HITL slice because it requires real LINE Developers credentials, webhook URL setup, and Leo's LINE user id from the live channel.

Acceptance criteria

• The bridge verifies X-Line-Signature from the raw LINE request body before parsing or business logic.
• The bridge has a documented setup flow for the L LINE channel credentials and webhook URL.
• The bridge captures or documents how to obtain Leo's LINE user id for owner allowlisting.
• Invalid signatures and disallowed sources are rejected with auditable logs that do not expose secrets.

Blocked by

• #23834
• Human setup: create/configure the LINE channel L, provide channel secret/access token, and capture Leo's LINE user id