Add Yield Farming & Rewards to Lending Contract

[ONEONUORA]

Component: Contracts (Lending) | Effort: 5-7 days | Priority: MEDIUM

Current State

Depositors earn interest but no additional rewards or yield farming.

Missing Functions

Yield farming functions:

• stake_lp_tokens() - Stake LP tokens for rewards
• unstake_lp_tokens() - Unstake LP tokens
• claim_rewards() - Claim accumulated rewards
• get_pending_rewards() - View pending rewards
• set_reward_rate() - Set reward emission rate (admin)
• get_staked_balance() - Get user's staked balance

Why This Matters

• Incentives: Attract more liquidity with rewards
• Competitive: Other protocols offer yield farming
• Growth: Rewards drive TVL growth
• Token utility: Use protocol token for rewards

Tasks

• Add RewardPool struct (total_staked, reward_rate, last_update)
• Add UserStake struct (amount, reward_debt, pending_rewards)
• Implement stake_lp_tokens() function
• Add unstake_lp_tokens() function
• Implement reward calculation logic
• Add claim_rewards() function
• Implement get_pending_rewards() view
• Add set_reward_rate() (admin only)
• Track total rewards distributed
• Add Staked, Unstaked, RewardsClaimed events
• Add tests for yield farming
• Document rewards mechanism

Acceptance Criteria

• Users can stake LP tokens
• Rewards calculated correctly over time
• Rewards claimable
• Reward rate adjustable by admin
• Tests cover reward scenarios
• Documentation explains yield farming