Hook System: Sender Identity & Channel Not Preserved

When Scotty (Pi) sends via hook to Ada (main), two issues:

Issue 1: Identity Not Preserved

Scotty sends → message appears as Ada not Scotty.

Current: Scotty → /hooks/agent → Ada's session → Delivered as Ada
Expected: Scotty → /hooks/agent → Ada's session → Delivered as Scotty

Issue 2: Wrong Delivery Channel

Scotty receives on Telegram → delivers to WhatsApp (wrong channel).

Current: Scotty on Telegram → hook → Delivered to WhatsApp
Expected: Scotty on Telegram → hook → Delivered to Telegram

Root Cause

1. /hooks/agent posts to main session which delivers as its agent
2. No fromAgentId field to preserve sender identity
3. No origin channel detection - defaults to active channel

Fix Approach

Add optional fields:

• fromAgentId - preserve sender identity
• originProvider / originChannelId - deliver to origin channel

See PR brief for technical details.

Offer: We can submit a PR for this fix if interested.