Add Gaggenau virtual integration docs (#38246)

Co-authored-by: Shay Levy <levyshay1@gmail.com>

source/_integrations/gaggenau.markdown

@@ -0,0 +1,35 @@
+---
+title: Gaggenau
+description: Connect and control your Gaggenau appliances using the Home Connect integration
+ha_category:
+  - Binary sensor
+  - Button
+  - Hub
+  - Light
+  - Number
+  - Select
+  - Sensor
+  - Switch
+ha_iot_class: Cloud Push
+ha_release: '2025.4'
+ha_domain: gaggenau
+ha_codeowners:
+  - '@DavidMStraub'
+  - '@Diegorro98'
+  - '@MartinHjelmare'
+ha_config_flow: true
+ha_platforms:
+  - binary_sensor
+  - button
+  - diagnostics
+  - light
+  - number
+  - select
+  - sensor
+  - switch
+ha_integration_type: virtual
+ha_supporting_domain: home_connect
+ha_supporting_integration: Home Connect
+---
+
+{% include integrations/supported_brand.md %}