--destructive-foreground was never defined in globals.css (light or dark
theme) — text-destructive-foreground resolved to nothing, so both the
clear-chat-history confirm button and recipe-form's discard-changes
confirm (same bg-destructive text-destructive-foreground pattern) fell
back to the default dark text color on a solid red background.
Added the missing variable (white, matching --primary-foreground's
light value — both themes use a saturated enough red that white stays
legible), mapped through @theme inline alongside the existing
--color-destructive.
Verified locally: screenshotted the clear-history confirm dialog,
button now shows white text on red.