Create Copilot setup workflow

[Copilot]

Description

Adds .github/workflows/copilot-setup-steps.yml to pre-configure GitHub Copilot's ephemeral development environment before it starts working on tasks.

The workflow:

• Sets up Python 3.9 with pip caching
• Installs dev dependencies via make install-dev
• Runs on workflow_dispatch and when the workflow file changes

This avoids Copilot's trial-and-error dependency installation process, providing immediate access to pytest, black, isort, ruff, and other dev tools.

Checklist

• I have updated the pyproject.toml

Original prompt

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This section details on the original issue you should resolve

<issue_title>Create copilot setup files</issue_title>
<issue_description>We need to setup the project to make copilot more effective following https://docs.github.com/en/copilot/how-tos/use-copilot-agents/coding-agent/customize-the-agent-environment</issue_description>

Comments on the Issue (you are Copilot in this section)

• Fixes Create copilot setup files #196

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[Copilot]

Pull request overview

This PR creates a GitHub workflow to pre-configure the development environment for GitHub Copilot's coding agent. The workflow sets up Python 3.9 with pip caching and installs development dependencies, enabling Copilot to start working immediately without trial-and-error dependency installation.

Changes:

• Added .github/workflows/copilot-setup-steps.yml workflow file
• Configured triggers for workflow_dispatch, push, and pull_request events when the workflow file changes
• Set up Python environment and dev dependency installation steps

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