The Shift+Ctrl+N hint under empty-state CTAs used alpha 0.65 at 0.82em,
which reads too faint on Adwaita light surfaces. Match other secondary
labels at alpha 0.78 so the accelerator stays quiet but legible.

Opened by TtyPolish

Co-authored-by: Lucenx9 <185146821+Lucenx9@users.noreply.github.com>