fix: implement support for tx_index column from Yaci-Store 2.0.0-beta to ensure
transactions are ordered correctly within blocks (0, 1, 2, ...) and in search results.
Changes:
- Added txIndex field to TxnEntity JPA entity
- Updated JOOQ Transaction and TransactionRecord classes to include TX_INDEX field
- Modified TxRepositoryQueryBuilder to select and map tx_index in queries
- Updated search query ordering to use (slot DESC, tx_index DESC)
- Updated block transaction query to order by tx_index ASC
This ensures:
- Transactions within blocks are returned in correct order (0, 1, 2, ...)
- Search results maintain proper chronological and within-slot ordering
- Consistent pagination for /search/transactions API
- Proper ordering for /block and /block/transaction endpoints