Fix new_task tool streaming by using correct ClineSayTool interface

- Changed 'message' property to 'content' in partial messages to match ClineSayTool interface
- This fixes the UI freezing issue where partial messages weren't streaming properly
- The 'message' property doesn't exist in ClineSayTool, causing the webview to not handle partial updates correctly
- Now consistent with other tools like writeToFileTool that use the correct interface properties

Author: roomote

src/core/tools/newTaskTool.ts

@@ -22,7 +22,7 @@ export async function newTaskTool(
 			const partialMessage = JSON.stringify({
 				tool: "newTask",
 				mode: removeClosingTag("mode", mode),
-				message: removeClosingTag("message", message),
+				content: removeClosingTag("message", message),
 			})
 
 			await cline.ask("tool", partialMessage, block.partial).catch(() => {})