Add vision model support and related configurations in Assistant

- Introduce new fields in AssistantConfig, schemas, and database models to support vision capabilities, including `vision_enabled` and `vision_model_resource_id`.
- Enhance validation logic in routes to ensure proper handling of vision models and their requirements.
- Update the AssistantPage and related frontend components to include options for enabling vision understanding and selecting appropriate vision models.
- Modify database seed scripts to include vision-related data for assistants, ensuring consistent setup.
- Refactor related functions to integrate vision model handling in the audio-visual processing pipeline.

frontend/src/lib/api.ts

@@ -128,6 +128,8 @@ export type Assistant = {
   runtimeMode: RuntimeMode;
   greeting: string;
   enableInterrupt: boolean;
+  visionEnabled: boolean;
+  visionModelResourceId: string | null;
   modelResourceIds: Partial<Record<ModelType, string>>;
   knowledgeBaseId: string | null;
   prompt: string;