fix(addon): create AI bot as internal user; use post_migrate_hook

- Bot needs to be a res.users to appear in Discuss DM search
- post_migrate_hook runs on both install and -u update
- Idempotent: skips creation if user already exists

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

addons/activeblue_ai/__manifest__.py

@@ -34,5 +34,6 @@ CRM, sales, project management, eLearning, expenses, and HR.
     'installable': True,
     'application': True,
     'auto_install': False,
-    'post_init_hook': '_create_ai_bot_partner',
+    'post_init_hook': '_ensure_ai_bot_user',
+    'post_migrate_hook': '_ensure_ai_bot_user',
 }