Add Dify integration and enhance workflow node specifications

- Introduce new fields `dify_api_url` and `dify_api_key` in `AssistantConfig` for Dify API integration.
- Update `requirements.txt` to include `dify-client-python` for Dify SDK support.
- Modify `config_resolver` to handle Dify connection information.
- Add a new `globalNode` type in workflow specifications to provide unified settings across workflows.
- Enhance node specifications with additional constraints and default values for better configuration management.
- Update frontend components to support the new `globalNode` type and its properties, improving workflow editor functionality.

backend/schemas.py

@@ -24,10 +24,10 @@ ToolParameterLocation = Literal["path", "query", "body", "header"]
 # 外部应用类型:其 config.apiKey 是该助手私有密钥,读时打码 / 写时哨兵
 EXTERNAL_TYPES = {"dify", "fastgpt", "opencode"}
 
-# 支持 realtime(语音到语音)的类型;外部托管大脑只能走 cascade。
+# MVP 仅 PromptBrain 支持 realtime;Workflow 和外部托管大脑只走 pipeline。
 # 与 services.brains 各 BrainSpec.supported_runtime_modes 对齐(此处独立声明,
 # 避免 HTTP schema 层为做校验而引入 pipecat 重依赖)。
-REALTIME_CAPABLE_TYPES = {"prompt", "workflow"}
+REALTIME_CAPABLE_TYPES = {"prompt"}
 
 
 class CamelModel(BaseModel):