Add the multi-company security rules for the landing.page model

energy_communities/security/ir_rule_data.xml

 <?xml version="1.0"?>
 <odoo>
+    <record model="ir.rule" id="landing_page_company_rule">
+        <field name="name">Landing Page multi-company</field>
+        <field name="model_id" ref="energy_communities.model_landing_page"/>
+        <field name="global" eval="True"/>
+        <field name="domain_force">['|', ('company_id', '=', False), ('company_id', 'in', company_ids)]</field>
+    </record>
+
     <record model="ir.rule" id="subscription_request_company_rule">
         <field name="name">Subscription Request multi-company</field>
         <field name="model_id" ref="cooperator.model_subscription_request"/>