Feat/web workflow improvements (#27981)

Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>
Co-authored-by: johnny0120 <johnny0120@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Wood <tuiskuwood@outlook.com>

api/core/tools/workflow_as_tool/provider.py

@@ -141,6 +141,7 @@ class WorkflowToolProviderController(ToolProviderController):
                         form=parameter.form,
                         llm_description=parameter.description,
                         required=variable.required,
+                        default=variable.default,
                         options=options,
                         placeholder=I18nObject(en_US="", zh_Hans=""),
                     )