Add a `LiquidityRepository.byAnchor(anchor)` method to list every asset balance for one anchor

[Jagadeeshftw]

📌 Description

LiquidityRepository exposes byAsset(asset) (used by QuoteService) but has no symmetric byAnchor(anchor) to list every asset balance held by a single anchor. LiquidityService/routes currently have no efficient way to answer "what does anchor X hold across all assets" without calling all() and filtering client-side.

🧩 Requirements and context

• Add byAnchor(anchor: string): LiquidityEntry[] to LiquidityRepository, mirroring the existing byAsset method's shape and doc-comment style.
• Add a corresponding LiquidityService.listByAnchor(anchor) and a GET /api/v1/liquidity/anchors/:anchor route (chosen to avoid colliding with the existing GET /:asset route).

🛠️ Suggested execution

• Add byAnchor to src/repositories/liquidityRepository.ts.
• Add listByAnchor to src/services/liquidityService.ts.
• Add the route to src/routes/liquidity.ts, taking care of route-ordering relative to the existing /:asset and /entries routes.
• Update src/openapi.ts with the new path.
• Add tests in src/repositories/liquidityRepository.test.ts, src/services/liquidityService.test.ts, and src/routes/liquidity.test.ts.

✅ Acceptance criteria

• byAnchor returns exactly the entries belonging to the given anchor across all assets.
• The new route doesn't shadow or get shadowed by /:asset or /entries, verified by a routing test.
• New tests pass at all three layers.

🔒 Security notes

N/A — read-only addition exposing data already reachable (less conveniently) via the existing unfiltered entries endpoint.

📋 Guidelines

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

[Agencybuilds]

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