Miscellaneous fixes (0.18 beta) (#23755)

* resolve saved credential sentinel to the stored api_key in the GenAI probe

* add profile faq

* center the multi-camera export time range on the current playback position

* add faq about preview restart cache

* clarify exports bulk download

docs/static/frigate-api.yaml

@@ -8244,6 +8244,11 @@ components:
       properties:
         provider:
           $ref: '#/components/schemas/GenAIProviderEnum'
+        name:
+          anyOf:
+            - type: string
+            - type: 'null'
+          title: Name
         api_key:
           anyOf:
             - type: string