Adds the first in-engine consumer of `ToastVariant::Warning` — a 4s
amber-bordered toast that fires once per daily-challenge date when the
player is within 30 minutes of UTC midnight reset and hasn't yet
completed today's challenge.
Mirrors the v0.21.2 `ToastVariant::Error` wiring: a domain-event
message (`WarningToastEvent(String)`) crosses the plugin boundary;
`animation_plugin::handle_warning_toast` reads it and spawns the
fire-and-forget toast. Suppression is decided by a pure helper
(`compute_expiry_warning_minutes`) that's exhaustively covered by 7
unit tests + 1 in-Bevy idempotence test.
After this lands, every `ToastVariant` (Info, Warning, Error,
Celebration) has at least one real driver — closing the "is this enum
scaffolding or load-bearing?" ambiguity that's been latent since the
variant was introduced.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
funman300
279e23d0af