* fix: return error on size mismatch in ReadNeedleMeta for consistency
When ReadNeedleMeta encounters a size mismatch at offset >= MaxPossibleVolumeSize,
it previously just continued without returning an error, potentially using wrong data.
This fix makes ReadNeedleMeta consistent with ReadBytes (needle_read.go), which
properly returns an error in both cases:
- ErrorSizeMismatch when offset < MaxPossibleVolumeSize (to trigger retry at offset+32GB)
- A descriptive error when offset >= MaxPossibleVolumeSize (after retry failed)
Fixes#7673
* refactor: use more accurate error message for size mismatch