chore(agents): add git-github agent skill

[spike-rabbit]

Add a git-github skill documenting the repository's Conventional Commit and pull request conventions for agent workflows.

Narrow the .prettierignore entry from the whole .agents directory to only the playwright-cli skill so the new skill is formatted.

---

Documentation.
Examples.
Dashboards Demo.
Playwright report.

Coverage Reports:

• charts-ng
• dashboards-ng
• element-ng
• element-translate-ng
• maps-ng
• native-charts-ng

[gemini-code-assist]

Code Review

This pull request adds a new documentation file detailing the Git and GitHub workflow guidelines for Siemens Element, and refines .prettierignore to target a specific subdirectory under .agents instead of ignoring the entire folder. The review feedback highlights minor grammatical errors and terminology inconsistencies in the newly added markdown file that should be corrected for better readability.

Important

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[ljanner]

It's a well written skill, I like it 👍

I'm wondering wether or not it's possible to define a single source of truth in a better way and for example pull the CONTRIBUTING.md into the skill.

There is an increasing amount of duplicate information in the skill and in other documentation around the repository this can end up in big maintenance efforts even for smaller changes and can cause inconsistency in the future.