add support for Base.repeat, Base.reverse & update README

[AFeuerpfeil]

This PR adds support for Base.repeat by enlarging the unit cell of the PeriodicArray and adjusting the map accordingly.

The README is also updated with new installation instructions after this package was registered in the julia General registry.

[codecov]

Welcome to Codecov 🎉

Once you merge this PR into your default branch, you're all set! Codecov will compare coverage reports and display results in all future pull requests.

ℹ️ You can also turn on project coverage checks and project coverage reporting on Pull Request comment

Thanks for integrating Codecov - We've got you covered ☂️

[Copilot]

Pull request overview

This PR adds support for Base.repeat to PeriodicArray by properly handling both inner and outer repetition while maintaining the periodic boundary conditions. The key innovation is adjusting the map function to account for the enlarged unit cell when using outer repetition.

Key changes:

• Implements Base.repeat for PeriodicArray with support for both inner and outer keyword arguments
• Correctly tiles the array with translated values using the original map function for outer repetition
• Creates a new map function that amplifies shifts to account for the larger super-cell structure
• Adds comprehensive tests for 1D and 2D cases with various translation functions

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/PeriodicArrays.jl	Implements Base.repeat for PeriodicArray with proper handling of inner/outer repetition and map transformation
test/test_nontrivial_boundary.jl	Adds comprehensive test coverage for 1D and 2D repeat operations with multiple translation functions

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-actions]

Your PR no longer requires formatting changes. Thank you for your contribution!