Blue public-view embed test

Throwaway page. If the board renders below, Blue public views can be embedded in Simplero.

Measured on the source before building this: x-frame-options is not set and the CSP says frame-ancestors * — so framing is explicitly allowed from any origin.

Blank frame = blocked despite the headers (a client-side buster, or the view needs a login). Board visible = embedding works and this pattern is reusable for any Blue public view.

Source: open the view directly — use this to tell "embedding is blocked" apart from "the view itself is empty".