Support referring foreign keys from other schemas

[Bouallegui-Moudhaffer]

Summary

This PR adds support for repacking tables that have referring foreign keys from other schemas.

Psycopack already tracked referring FK schema metadata, but it still rejected cross-schema referring FKs in pre_validate() and assumed FK-related DDL would always run against self.schema. This PR removes that limitation and makes FK handling schema-aware throughout the repack lifecycle.

Changes

• remove the cross-schema referring FK rejection in pre_validate()
• make FK constraint DDL schema-aware
• fix get_referring_fks() to resolve referred tables against the correct schema and check ownership against the actual referring table schema
• update reset / cleanup / stale-copy cleanup paths to operate on the real referring table schema
• make cleanup FK restoration more robust by matching replacement FKs via deterministic temp names
• preserve FK validation state during cleanup/retry flows

Tests

• add regression coverage for referring FKs from another schema
• cover both DIRECT_TRIGGER and CHANGE_LOG
• keep existing reentrant / idempotent behavior green

Validation

Ran locally:

• pytest tests/test_repack.py
• ruff check .
• mypy .

All passed.

[marcelofern]

Hi @Bouallegui-Moudhaffer, thanks for your contribution. I will have a look at when I'm available next week.
In the meanwhile, could I ask you what has been your use case for psycopack?

[Bouallegui-Moudhaffer]

Hi @Bouallegui-Moudhaffer, thanks for your contribution. I will have a look at when I'm available next week. In the meanwhile, could I ask you what has been your use case for psycopack?

Thanks for the note @marcelofern.

I’m genuinely interested in Kraken and potentially joining in the future, so I wanted to get more familiar with the tech you’re building. I’ve been going through Kraken Tech and OctoEnergy’s public repositories, especially around data engineering topics.

As I was reviewing this repo, I spotted an area where I felt I could contribute something useful, so I took the opportunity to work on it.

Thanks again for the feedback, I really appreciate it.