Dynamically enable/disable GenAI (#19139)

* config

* dispatcher and mqtt

* docs

* use config updater

* add switch to frontend

docs/docs/configuration/genai.md

@@ -21,7 +21,7 @@ genai:
   model: gemini-1.5-flash
 
 cameras:
-  front_camera: 
+  front_camera:
     genai:
       enabled: True # <- enable GenAI for your front camera
       use_snapshot: True
@@ -30,7 +30,7 @@ cameras:
       required_zones:
         - steps
   indoor_camera:
-    genai: 
+    genai:
       enabled: False # <- disable GenAI for your indoor camera
 ```
 
@@ -38,6 +38,8 @@ By default, descriptions will be generated for all tracked objects and all zones
 
 Optionally, you can generate the description using a snapshot (if enabled) by setting `use_snapshot` to `True`. By default, this is set to `False`, which sends the uncompressed images from the `detect` stream collected over the object's lifetime to the model. Once the object lifecycle ends, only a single compressed and cropped thumbnail is saved with the tracked object. Using a snapshot might be useful when you want to _regenerate_ a tracked object's description as it will provide the AI with a higher-quality image (typically downscaled by the AI itself) than the cropped/compressed thumbnail. Using a snapshot otherwise has a trade-off in that only a single image is sent to your provider, which will limit the model's ability to determine object movement or direction.
 
+Generative AI can also be toggled dynamically for a camera via MQTT with the topic `frigate/<camera_name>/genai/set`. See the [MQTT documentation](/integrations/mqtt/#frigatecamera_namegenaiset).
+
 ## Ollama
 
 :::warning
@@ -202,7 +204,7 @@ genai:
     car: "Observe the primary vehicle in these images. Focus on its movement, direction, or purpose (e.g., parking, approaching, circling). If it's a delivery vehicle, mention the company."
 ```
 
-Prompts can also be overriden at the camera level to provide a more detailed prompt to the model about your specific camera, if you desire. 
+Prompts can also be overriden at the camera level to provide a more detailed prompt to the model about your specific camera, if you desire.
 
 ```yaml
 cameras:

docs/docs/integrations/mqtt.md

@@ -411,6 +411,14 @@ Topic to turn review detections for a camera on or off. Expected values are `ON`
 
 Topic with current state of review detections for a camera. Published values are `ON` and `OFF`.
 
+### `frigate/<camera_name>/genai/set`
+
+Topic to turn generative AI for a camera on or off. Expected values are `ON` and `OFF`.
+
+### `frigate/<camera_name>/genai/state`
+
+Topic with current state of generative AI for a camera. Published values are `ON` and `OFF`.
+
 ### `frigate/<camera_name>/birdseye/set`
 
 Topic to turn Birdseye for a camera on and off. Expected values are `ON` and `OFF`. Birdseye mode