Adds a spend-coins-for-a-random-reward mini-game reachable from the
shop. Backend mirrors the store's existing atomic/idempotent purchase
pattern (SpinAsync in CreditStore.cs) with a server-authoritative,
weighted reward roll and a rolling per-user spin-rate guard; odds are
served from GET /api/credits/spin-config so the client never hardcodes
numbers that could drift from the real payout table. The mockup's
"Streak Protector" reward was swapped for a real Exam Simulation Token
since streaks aren't currently a persisted, protectable concept.
Also fixes two latent bugs surfaced while building this:
- credits_service.gd's operation-id builder referenced a nonexistent
AuthState.user_id (should be .username), throwing on every credit
action.
- _post() silently no-op'd with no signal when signed out, which
combined with a GDScript closure gotcha (lambdas capture outer
locals by value, so reassigning inside one never reached the
caller) meant a spin attempted while unauthenticated could hang
forever instead of surfacing an error.
Matches the latest reference more closely: a Featured/Tokens/Boosts/
Content/Customization/Bundles tab row (only Featured is populated -
the rest are inert labels since there's no real data behind them
yet), per-card checkmark feature bullets, and a Popular badge on the
Exam Simulation Token card. Client-side presentation only, no backend
changes.
Replaces the plain title/list layout with a header, a coin-balance
summary card, and a product card grid (icon, description, price,
solid Buy button) matching the app's existing card/badge visual
language. Only the two real products render - no fabricated
categories or bundles, since the backend doesn't have that data yet.
hz