Add docs for upcoming Helios integration

source/_integrations/helios.markdown

@@ -0,0 +1,107 @@
+---
+title: Helios
+description: Instructions on how to integrate Helios ventilation units into Home Assistant.
+ha_category:
+  - Fan
+  - Sensor
+  - Switch
+ha_config_flow: true
+ha_release: 2026.2
+ha_iot_class: Local Polling
+ha_domain: helios
+ha_platforms:
+  - binary_sensor
+  - date
+  - fan
+  - number
+  - sensor
+  - switch
+ha_codeowners:
+  - '@helios-ventilatoren-com'
+ha_integration_type: integration
+---
+
+The **Helios** {% term integration %} lets you control any [Helios ventilation unit](https://www.heliosventilatoren.de/en/products/ventilation-with-heat-recovery/domestic-units-for-wall-ceiling-installation) that is supported by the [helios_websocket_api](https://github.com/helios-ventilatoren-com/helios_websocket_api) (follow the link for a list of supported units). 
+
+{% include integrations/config_flow.md %}
+
+## Supported functionality
+
+### Fan
+
+The fan platform of this integration allows you to control the entire unit. You can turn the unit on/off using the toggle switch, adjust the fan speed, and select a ventilation profile.
+
+### Sensor
+
+The sensor platform allows you to monitor various metrics such as fan speeds, air temperatures, humidity, remaining filter life, cell state, and more.
+
+### Binary sensor
+
+The binary sensor platform allows you to monitor the status of the post heater.
+
+### Switch
+
+The switch platform allows you to lock the heat recovery bypass.
+
+### Number
+
+The number platform gives you control over the supply air temperatures.
+
+### Date
+
+The date platform allows you to set the filter change date.
+
+
+## Profile switching
+
+For convenient switching of ventilation profiles in the GUI, select the `Helios` fan {% term entity %} to get a drop-down menu to select from. Alternatively, the action `fan/set_preset_mode` can be used.
+
+The four standard Vallox profiles are supported:
+
+- `Home`
+- `Away`
+- `Boost`
+- `Fireplace`
+
+## Fan actions
+
+### Action: Set profile fan speed home `
+
+The `helios.set_profile_fan_speed_home` action sets the fan speed of the `Home` profile.
+
+- **Data attribute**: `set_profile_fan_speed_home`
+    - **Description**: Fan speed in %. `Integer`, between 0 and 100.
+    - **Optional**: No
+
+### Action: Set profile fan speed away 
+
+The `helios.set_profile_fan_speed_away` sets the fan speed of the `Away` profile.
+
+- **Data attribute**: `set_profile_fan_speed_away`
+    - **Description**: Fan speed in %. `Integer`, between 0 and 100.
+    - **Optional**: No
+
+### Action: Set profile fan speed boost 
+
+The `helios.set_profile_fan_speed_boost` action sets the fan speed of the `Boost` profile.
+
+- **Data attribute**: `set_profile_fan_speed_boost`
+    - **Description**: Fan speed in %. `Integer`, between 0 and 100.
+    - **Optional**: No
+
+### Action: Set profile
+
+The `helios.set_profile` sets the profile and, optionally, the duration for which the profile is active. 
+
+- **Data attribute**: `profile`
+    - **Description**: Profile to set, one of `home`, `away`, `boost`, `fireplace`, or `extra`.
+      - **Optional**: No
+- **Data attribute**: `duration`
+    - **Description**: Duration to activate the profile for; in minutes. `Integer` between 1 and 65535. Only applies to  `boost`, `fireplace`, or `extra` profiles. 65535 sets the profile without a timeout.
+        - **Optional**: Yes
+
+## Removing the integration
+
+This integration follows standard integration removal.
+
+{% include integrations/remove_device_service.md %}