feat: add offset diagnostic logging and max_records_per_run limit

[halconel]

Summary

• Add max_records_per_run parameter to limit records processed per run
• Add diagnostic logging when offset is not calculated (empty output, NULL max_update_ts)
• Add diagnostic logging when offset is not updated in run_full

Motivation

After PR #372 merge, analysis showed that 34% of transformations (73/215) have stuck offsets despite successful processing. This PR adds:

1. Protection against processing millions of records in single run
2. Diagnostic logging to identify WHY offset updates fail

Changes

• Added max_records_per_run parameter to BaseBatchTransformStep.__init__
• Applied SQL LIMIT in get_full_process_ids when max_records_per_run is set
• Added logging in store_batch_result when offset not calculated
• Added logging in run_full when changes.offsets is empty
• Updated BatchTransform and DatatableBatchTransform dataclasses