Add validation for round consistency

This validation is inspired by the investigation of https://github.com/hiero-ledger/hiero-consensus-node/issues/21549

Among other things, we discovered that we observe discrepancy of a round value between directory name where a snapshot is stored to (a round number), `ROUND` parameter in `stateMetadata.txt` file and `round` parameter in `ConsensusSnapshot` object from `PlatformStateService`. All three parameters must have exactly the same value.

Start by locating the snapshot persistence and validation entry points that handle the directory name, stateMetadata.txt, and PlatformStateService's ConsensusSnapshot. Trace how each round value is read, then add validation that all three values match; done means discrepancies are detected and covered by the relevant tests.

Written by the indexing model from the issue text.