`/account/coins` ignores currencies parameter

The `/account/coins` endpoint does not filter UTXOs by the `currencies` parameter as specified in the Rosetta spec.

**Expected Behavior**:
When `currencies` parameter is provided, should return only UTXOs containing the specified currencies.

**Actual Behavior**:
Returns all UTXOs regardless of currencies parameter.

**Reproduce**:
```bash
curl -X POST http://localhost:8082/account/coins \
-H "Content-Type: application/json" \
-d '{
"network_identifier": {"blockchain": "cardano", "network": "preprod"},
"account_identifier": {"address": "addr_test1qrtdh7587yz5m2w504sjhqnrfml5fpcuxu24fj8xwvk48artcrahhulmvvsnmwqk2k3nmrz20sw8uj7htlpnlutk0p9sjfnd3n"},
"currencies": [{"symbol": "ADA", "decimals": 6}]
}'
```

**Expected**: Returns subset of UTXOs (only ADA-only UTXOs, excluding multi-asset UTXOs)
**Actual**: Returns all 236 UTXOs including those with native assets

**Spec Reference**:
- Mesh docs: https://docs.cdp.coinbase.com/api-reference/mesh/account/get-an-account-unspent-coins.

**Note**: `/account/balance` currencies filter works correctly on rosetta-java v1.3.3.