feat(addon): add ActiveBlue AI bot to Odoo Discuss

- Create res.partner for the AI bot (appears in DM contacts)
- Override mail.channel.message_post to intercept direct messages
  to the bot partner and forward them to the agent service
- Post the agent reply back into the Discuss channel as the bot
- Add discuss to depends; load res_partner_bot.xml data

Users can now open Discuss -> New Message -> search 'ActiveBlue AI'
to start a conversation with the agent.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

addons/activeblue_ai/data/res_partner_bot.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+    <data noupdate="1">
+        <record id="partner_activeblue_ai" model="res.partner">
+            <field name="name">ActiveBlue AI</field>
+            <field name="active">True</field>
+            <field name="partner_share">False</field>
+            <field name="comment">AI assistant — send a direct message to chat</field>
+        </record>
+    </data>
+</odoo>