Add a withdrawal audit trail to `LiquidityService.withdrawLiquidity` distinct from the balance mutation itself

[Jagadeeshftw]

📌 Description

LiquidityService.withdrawLiquidity mutates (or removes) the LiquidityEntry for an anchor/asset pair but keeps no record of the withdrawal event itself — once a balance reaches zero and the entry is removed via this.repo.remove(anchor, asset), there is no trace anywhere (besides the generic mutating-request auditLog.ts middleware, which only records method/path/status, not amounts) of how much was withdrawn or when.

🧩 Requirements and context

• Add an in-memory withdrawal history (e.g. a BoundedHistory<WithdrawalRecord> in LiquidityService, mirroring the pattern already used by routes/metrics.ts) recording { anchor, asset, amount, remainingBalance, timestamp } for every successful withdrawal.
• Expose the history via a new read method, e.g. LiquidityService.listWithdrawals().
• Add a corresponding GET /api/v1/liquidity/withdrawals route.

🛠️ Suggested execution

• Modify src/services/liquidityService.ts to record a withdrawal entry using src/utils/history.ts's BoundedHistory inside withdrawLiquidity.
• Add the GET /withdrawals route to src/routes/liquidity.ts.
• Update src/openapi.ts with the new path.
• Add tests in src/services/liquidityService.test.ts and src/routes/liquidity.test.ts.

✅ Acceptance criteria

• Every successful withdrawal is recorded with amount, resulting balance, and timestamp.
• GET /api/v1/liquidity/withdrawals returns the recorded history, bounded by the same pattern as other BoundedHistory usages.
• New tests pass; existing withdrawLiquidity tests unaffected.

🔒 Security notes

N/A — additive read-only audit trail improving traceability of a mutating financial operation, itself a security-positive change.

📋 Guidelines

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