feat: add configurable vision focus prompts

backend/schemas.py

@@ -198,6 +198,7 @@ class AssistantUpsert(CamelModel):
     startup: StartupConfig = Field(default_factory=StartupConfig)
     vision_enabled: bool = False
     vision_model_resource_id: str | None = None
+    vision_focus_prompt: str = Field(default="", max_length=4000)
     model_resource_ids: dict[ModelType, str] = Field(default_factory=dict)
     knowledge_base_id: str | None = None
     knowledge_retrieval_config: KnowledgeRetrievalConfig = Field(
@@ -263,6 +264,15 @@ class AssistantOut(AssistantUpsert):
     updated_at: str | None = None
 
 
+class VisionFocusPromptGenerateRequest(CamelModel):
+    source_prompt: str = Field(min_length=1, max_length=20000)
+    model_resource_id: str = Field(min_length=1, max_length=40)
+
+
+class VisionFocusPromptGenerateResult(CamelModel):
+    focus_prompt: str
+
+
 class DynamicVariableDefinition(CamelModel):
     type: DynamicVariableType = "string"
     required: bool = False