Add a `lastUpdated` timestamp to the `Pool` interface in `models/liquidity.ts` so clients can tell how fresh aggregated data is

[Jagadeeshftw]

📌 Description

LiquidityEntry carries an updatedAt timestamp, but the aggregated Pool interface ({ asset, total, anchors }, computed on-the-fly by LiquidityRepository.pools()) has no timestamp at all. A client reading GET /api/v1/liquidity or GET /api/v1/liquidity/:asset has no way to tell how recently any of the underlying entries changed without separately fetching /entries and computing a max updatedAt themselves.

🧩 Requirements and context

• Add an optional lastUpdated?: string field to the Pool interface, computed as the max updatedAt across the asset's contributing LiquidityEntry records.
• Compute it in LiquidityRepository.pools() alongside the existing total/anchors aggregation, with no extra full-table pass.
• Update LiquidityService.listPools/getPool callers implicitly (no code change needed if they just pass the Pool through) and openapi.ts's documented response shape.

🛠️ Suggested execution

• Modify src/repositories/liquidityRepository.ts's pools() method to track and set lastUpdated while iterating entries.
• Modify src/models/liquidity.ts's Pool interface.
• Update src/openapi.ts's /api/v1/liquidity and /api/v1/liquidity/{asset} response documentation.
• Add tests in src/repositories/liquidityRepository.test.ts and src/services/liquidityService.test.ts asserting lastUpdated reflects the most recent contributing entry's updatedAt.

✅ Acceptance criteria

• Pool.lastUpdated reflects the maximum updatedAt among the asset's entries.
• GET /api/v1/liquidity and GET /api/v1/liquidity/:asset include the new field.
• New tests pass; existing pool-shape tests are extended, not broken, by the additive field.

🔒 Security notes

N/A — read-only freshness metadata over already-exposed aggregate data.

📋 Guidelines

• Minimum 95% test coverage
• Clear documentation
• Timeframe: 96 hours

[Agencybuilds]

Would love to work on this issue will produce an excellent result