feat: Add dummy endpoint for fetching user LP rewards and yield

[AlAfiz]

Description

On the frontend Portfolio page, users want to see how much money they are making from their deposited liquidity.
We need a backend endpoint that calculates (or currently mocks) their pending rewards based on their wallet address.
This endpoint will return the total yield earned in USD and the equivalent in the specific pool tokens.
This data is the primary hook that keeps Liquidity Providers coming back to the app daily.

Requirements

• Create a GET route at /api/v1/users/:address/rewards.
• Generate a dummy JSON object containing totalEarnedUSD and a breakdown of pendingTokens per pool.
• Include a mock lastCompounded timestamp.
• Return the payload wrapped in our standard successResponse formatter.