[Feature] Subscription tiers — design and implementation

[iiamlewis]

Overview

Three subscription tiers gating premium features and better caps-to-plutonium conversion rates. Name colours tied to tier. Name colour drops if subscription lapses.

Scope

• Three tiers (names/prices defined in product decision issue)
• Caps-to-plutonium conversion rate increases per tier
• Tier-specific name colour: entry = blue, mid = green, top = gold
• Name colour removed if subscription lapses
• Stripe subscription integration
• Subscriber status reflected in-game and on profile

Acceptance criteria

• Three tiers purchasable via Stripe
• Correct conversion rate applied per tier
• Name colour applied in-game on subscription activation
• Name colour removed on subscription lapse (not on next renewal attempt — immediately)
• Subscriber badge visible on profile
• Subscription management (cancel, upgrade, downgrade) via account settings

Dependencies

• Depends on: OAuth / Google login, Subscription packages product decision
• Blocks: Ad-free, Vote for map, Free monthly cosmetics, Battle Pass free access