Native alert() and confirm() render their buttons in the browser or OS
locale, so on a German system prompts such as the Clear Screen Wall
confirmation showed German labels that disagreed with the rest of the
web UI. Both are now served by a single themed modal that reuses the
logout confirmation styling: an info variant with one OK button for
notices, and a danger variant with Cancel/OK for destructive actions.
The alert helper is fire-and-forget, while the confirm helper returns a
Promise, so the two call sites that need an answer (clearWall and
deleteUser) are now async. Dialog title and message are written with
textContent so device names, user names and server error strings can
never be interpreted as markup. A pending dialog is resolved as
cancelled when another one supersedes it, keeping callers from hanging,
and clicking the backdrop or pressing Escape closes the dialog. Remote
keyboard forwarding now ignores keys while a dialog is open.
Co-Authored-By: deepseek-flash
