CI: add commit message style check workflow

[tuhaihe]

This commit introduces a new GitHub Actions workflow that checks commit messages in pull requests against recommended style guidelines.

The workflow verifies:

• Title length (50 characters or less)
• Title starts with uppercase letter
• Body is not empty
• Body lines don't exceed 72 characters

The check provides helpful suggestions to contributors without preventing PR merging.

Fixes #ISSUE_Number

What does this PR do?

Type of Change

• [ ] Bug fix (non-breaking change)
• [ ] New feature (non-breaking change)
• [ ] Breaking change (fix or feature with breaking changes)
• [ ] Documentation update

Breaking Changes

Test Plan

• [ ] Unit tests added/updated
• [ ] Integration tests added/updated
• [ ] Passed make installcheck
• [ ] Passed make -C src/test installcheck-cbdb-parallel

Impact

Performance:

User-facing changes:

Dependencies:

Checklist

• [ ] Followed contribution guide
• [ ] Added/updated documentation
• [ ] Reviewed code for security implications
• [ ] Requested review from cloudberry committers

Additional Context

CI Skip Instructions

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[tuhaihe]

• Good case: https://github.com/apache/cloudberry/actions/runs/17064472353?pr=1177
• Bad test case: https://github.com/tuhaihe/cloudberrydb/actions/runs/17063585469