Contracts: Staking Pool contract (minimal skeleton)

Context

We want a staking pool for rent funding + profit sharing (future). We need a safe minimal MVP contract first.

Goal

Create a Soroban staking pool contract skeleton.

MVP Functions

• init(admin: Address, token: Address)
• stake(user: Address, amount: i128)
• unstake(user: Address, amount: i128)
• staked_balance(user: Address) -> i128
• total_staked() -> i128
• pause/unpause
• emit events on stake/unstake

Notes

• Token is USDC contract Address
• Amounts are i128, must be positive
• Authorization:
  • user must auth for stake/unstake
  • admin can pause/unpause

Acceptance Criteria

• Unit tests cover stake/unstake edge cases
• Event topics standardized:
  • ("stake", user)
  • ("unstake", user)
• cargo test passes