SingleFile CLI 2.18.5

CLI fixes and improvements

Update single-file-core to 1.6.35: a frame that failed to load (blocked by X-Frame-Options, unreachable host, dead embed) shows the browser's error page, where the frame capture script cannot run, so the page used to wait 5 s for it on every save; it now waits 2 s. The :first-letter style is read only on block containers when collecting the used fonts, as the pseudo-element does not apply to inline elements. Since 1.6.33, a video whose poster could not be captured gets a blank poster instead of failing the capture when the page is processed without a live document.

Co-authored by Claude (Claude Code)