Extract branch name when in detached mode

[efrecon]

Prefer known environment variables set by software forges during CI.

Use git name-rev when in detached mode. Detect detached mode by running git symbolic-ref and let it fail when detached.

Whenever necessary, analyze the branch in chunks separated by / and skip the two first ones, this is because git name-rev adds remotes/origin.

Close #1

[Copilot]

Pull Request Overview

This PR enhances the branch name detection functionality to work reliably in detached HEAD state, which commonly occurs in CI environments during pull/merge requests. The implementation adds fallback mechanisms to extract branch names from CI environment variables and uses git name-rev when git symbolic-ref fails.

• Enhanced branch detection with CI environment variable support for GitHub Actions, GitLab CI, and Bitbucket Pipelines
• Added fallback to git name-rev when in detached HEAD state
• Improved error handling and user feedback for branch name determination failures

Reviewed Changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 4 comments.

File	Description
pre_commit_hooks/branch_check.py	Adds get_forge_branch() and get_branch_name() functions with enhanced branch detection logic
README.md	Documents the new branch detection behavior and fallback mechanisms
.github/workflows/CI.yml	Adds GitHub Actions workflow for continuous integration testing
.github/pre-commit-config.yaml	Adds pre-commit configuration for testing the branch check hook

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