feat: Replace Console logging in VectorDatabase with ILogger

# 🎉 Pull Request Template

📝 Description

Replaces current Console.WriteLine calls by using .NET's standard logging abstraction.

✅ Checklist

Before submitting this pull request, please make sure you've completed the following:

[X] I have read the CONTRIBUTING document. 📚
[X] My code follows the project's coding style and conventions. 📐
[X] I have added tests that prove my fix is effective or that my feature works as intended. 🧪
[X] I have commented my code, particularly in hard-to-understand areas. 💬
[ ] I have made corresponding changes to the documentation, if necessary. 📖 (N/A)
[X] My changes generate no new warnings or errors. ⚠️

🔗 Related Issues

Contributes to #22.

📷 Screenshots

N/A

💡 Additional Notes

Mocks

I needed some mocks to validate that correct log messages and other properties. To do that, I added some manual Mocks in the Neighborly.Tests.Helpers namespace, because I didn't see any mocking library in use. Please let me know if you'd rather use some mocking library, or don't log messages to be tested in that level of detail.

Serilog/NLog

I didn't want to decide on a logging framework for you, but it should be easy enough to plugin in a different one later. Generally, I think it might be a good idea to also log to OTEL and provide some metrics.

nickna / Neighborly