Mainnet contract deployment

[akawolfcito]

Description

Deploy all 4 contracts to Stacks mainnet and update web app addresses.

Blocked By

• Partner confirmation (Jardin Botanico)
• Treasury funding ($30-50 USD)

Deployment Order

1. plant-storage (immutable data layer)
2. plant-game-v1 (game logic)
3. plant-nft-v2 (SIP-009 NFT)
4. impact-registry (graduation + redemption tracking)

Acceptance Criteria

• All 4 contracts deployed to mainnet
• Contract addresses updated in apps/web/src/constants/contracts.ts
• Verified on Hiro Explorer
• Mint + water tested on mainnet
• Cooldown set to 144 blocks (~24h)