fix(ui): hide token modal backdrop when dismissed
The "copy your new token" modal applied x-show only to the inner
card, so the dark backdrop and click-blocking overlay stayed in the
DOM after the user clicked "I have stored it safely", leaving the
page unusable until reload. Move x-show onto the backdrop wrapper so
the whole modal hides together.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>