fix(addon): resolve all Odoo 18 install errors

- security/res_groups.xml: fully qualify ref('group_ai_user') with module prefix
- data/ir_cron.xml: remove numbercall field (removed in Odoo 17/18)
- views/menus.xml: remove web_icon referencing missing static/src/img/icon.png
- controllers/webhook.py: use get_json() instead of deprecated json.loads(data)
- security/ir.model.access.csv: use fully-qualified group external IDs (prior commit)

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

addons/activeblue_ai/controllers/webhook.py

@@ -25,9 +25,8 @@ class AiWebhookController(http.Controller):
         if bot and bot.webhook_secret:
             pass  # IP check handled at network level via ALLOWED_CALLBACK_IP env var in agent service
 
-        try:
-            data = json.loads(request.httprequest.data)
-        except Exception:
+        data = request.httprequest.get_json(silent=True) or {}
+        if not data:
             return Response(status=400)
 
         event_type = data.get('event', '')