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/security/res_groups.xml

@@ -16,7 +16,7 @@
         <record id="group_ai_manager" model="res.groups">
             <field name="name">AI Manager</field>
             <field name="category_id" ref="module_activeblue_ai"/>
-            <field name="implied_ids" eval="[(4, ref('group_ai_user'))]"/>
+            <field name="implied_ids" eval="[(4, ref('activeblue_ai.group_ai_user'))]"/>
             <field name="users" eval="[(4, ref('base.user_root')), (4, ref('base.user_admin'))]"/>
             <field name="comment">Can configure AI, approve directives, and view all logs</field>
         </record>