Test v1.6.2 on macOS: 'Build from an idea'

[Jing-yilin]

@j-yw could you test the latest release, v1.6.2, on your Mac?

1. Install the dmg for your architecture, or let an existing install update itself.
2. On the home page, try Build from an idea: describe a small app idea and let the agent make the project.
3. Check that the project opens, and that the PRD and first boards appear on the canvas.

Please comment with what worked and what didn't. Screenshots are welcome.