feat(workflow): add per-agent vision configuration

backend/services/workflow/agent.py

@@ -11,6 +11,7 @@ from pipecat.services.settings import LLMSettings
 
 from services.brains.base import BrainRuntime
 from services.runtime_variables import DynamicVariableStore
+from services.vision import VISION_SYSTEM_HINT
 from services.workflow_engine import WorkflowEngine
 from services.workflow_router import WorkflowLLMRouter
 
@@ -39,6 +40,9 @@ class WorkflowAgentStage:
 
     def role_message(self, node_id: str) -> str:
         stage_prompt = self._engine.prompt_for(node_id, self._store)
+        stage = self._engine.agent_stage_config(node_id)
+        if stage.vision_enabled:
+            stage_prompt = f"{stage_prompt}\n\n[视觉能力]\n{VISION_SYSTEM_HINT}"
         return (
             f"{stage_prompt}\n\n[工作流执行规则]\n"
             f"{AGENT_STAGE_INSTRUCTION}"
@@ -90,6 +94,14 @@ class WorkflowAgentStage:
                     "score_threshold": stage.knowledge_score_threshold,
                 }
             )
+        if self._runtime.set_vision_scope:
+            self._runtime.set_vision_scope(
+                {
+                    "enabled": stage.vision_enabled,
+                    "vision_model_resource_id": stage.vision_model_resource_id,
+                    "llm_resource_id": stage.llm_resource_id,
+                }
+            )
 
     def node_config(
         self,