Currency filter + limit causes timeout

### Context & versions
- **Version**: rosetta-java v1.3.3
- **Network**: preprod
- **Endpoint**: `/search/transactions`

### Steps to reproduce
```bash
# This query times out (>600s)
curl -X POST http://localhost:8082/search/transactions \
-H "Content-Type: application/json" \
-d '{
"network_identifier": {"blockchain": "cardano", "network": "preprod"},
"currency": {"symbol": "tTEURO", "decimals": 2},
"limit": 1
}'

# This query works fast (~2s)
curl -X POST http://localhost:8082/search/transactions \
-H "Content-Type: application/json" \
-d '{
"network_identifier": {"blockchain": "cardano", "network": "preprod"},
"currency": {"symbol": "tTEURO", "decimals": 2}
}'
```

### Actual behavior
When combining `currency` parameter with explicit `limit` parameter, the query performs full blockchain scan and times out after 600+ seconds.

### Expected behavior
Query with `currency` filter and `limit=1` should return quickly (within 2-3 seconds), returning first matching transaction.

**Workaround**: Omit `limit` parameter when using `currency` filter - uses default limit (100) and completes in ~2s.

Start at the `/search/transactions` endpoint and reproduce both curl requests against the preprod configuration, comparing the currency-only query with the same query using `limit=1`. Trace how the currency filter and explicit limit are combined, then verify that the limited request returns the first matching transaction within a few seconds without scanning the full blockchain.

Written by the indexing model from the issue text.