modified save_site_database.py for nl and added new tests

[spyke7]

Pull Request

Description

This PR adds validation for Netherlands (NL) solar capacity data to prevent inconsistent (“funky”) regional capacity values from being saved to the site database.

A new helper function validate_nl_capacities checks, per timestamp, that the sum of regional capacities (regions 1–12) matches the national capacity (region 0) within a configurable tolerance (default 0.1%). If the validation fails, the save process is aborted to avoid persisting bad data.

The validation is integrated into save_generation_to_site_db() and only runs for NL data when the required columns (capacity_kw, region_id) are present.

Fixes #135

How Has This Been Tested?

Unit tests were added to cover:

• Valid capacity data passing validation
• Regional capacities that are too high or too low failing validation
• Edge cases within the documented tolerance (~30 MW for NL)

Integration tests were added to ensure:

• save_generation_to_site_db() aborts when NL capacity validation fails

• Data is correctly saved when NL capacity validation passes

• Yes

If your changes affect data processing, have you plotted any changes? i.e. have you done a quick sanity check?

• Yes

Checklist:

• My code follows OCF's coding style guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked my code and corrected any misspellings

[peterdudfield]

It looks like lots of these changes are formatting ones. Would you be able to split this PR into Formatting and NL tests?

[spyke7]

I did black . as written in the README.md, that's why the files are formatted

[spyke7]

Should I do it without doing the black . and push it?