feat: 接入新动作 update_canvas

app/schemas/actions/update_canvas.py

@@ -0,0 +1,17 @@
+"""仅更新画布属性，不修改组件或数据源"""
+
+from typing import Literal
+
+from pydantic import Field, JsonValue
+
+from app.schemas.base import NonBlankString
+
+from .base import ActionModel
+
+
+class UpdateCanvasAction(ActionModel):
+    type: Literal["update_canvas"] = "update_canvas"
+    properties: dict[NonBlankString, JsonValue] = Field(
+        min_length=1,
+        description="要替换的 canvas 顶层字段，如 width、height、backgroundColor；未提供的字段保持不变",
+    )