Feat: add canvas_category field for UserCanvas and CanvasTemplate (#9885)

### What problem does this PR solve?

Add `canvas_category` field for UserCanvas and CanvasTemplate.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

api/db/__init__.py

@@ -74,8 +74,10 @@ class TaskStatus(StrEnum):
     DONE = "3"
     FAIL = "4"
 
+
 VALID_TASK_STATUS     = {TaskStatus.UNSTART, TaskStatus.RUNNING, TaskStatus.CANCEL, TaskStatus.DONE, TaskStatus.FAIL}
 
+
 class ParserType(StrEnum):
     PRESENTATION = "presentation"
     LAWS = "laws"
@@ -105,10 +107,19 @@ class CanvasType(StrEnum):
     DocBot = "docbot"
 
 
+class CanvasCategory(StrEnum):
+    Agent = "agent_canvas"
+    DataFlow = "dataflow_canvas"
+
+VALID_CAVAS_CATEGORIES = {CanvasCategory.Agent, CanvasCategory.DataFlow}
+
+
 class MCPServerType(StrEnum):
     SSE = "sse"
     STREAMABLE_HTTP = "streamable-http"
 
+
 VALID_MCP_SERVER_TYPES = {MCPServerType.SSE, MCPServerType.STREAMABLE_HTTP}
 
+
 KNOWLEDGEBASE_FOLDER_NAME=".knowledgebase"