Add CI validation for GitHub metadata and release intro files

[Madhan230205]

Overview

Add CI checks to validate metadata/release automation prerequisites before maintainers cut tags.

User Story

As a maintainer
I want CI to validate release metadata files
So that configuration mistakes are caught before publishing.

Context

• Current checks validate version alignment, but not all metadata prerequisites.
• Pain point: late failures or silent metadata drift.
• Success metric: CI fails fast with actionable errors when required metadata files are invalid.

Acceptance Criteria

• CI validates .github/settings.yml exists and has required keys.
• CI validates .github/release-intro.md exists and is non-empty.
• Error messages are explicit and actionable.
• Checks run on pull requests targeting main.

Technical Requirements

• Technology/framework: lightweight script in CI (Python/yq/grep-based)
• Security: no elevated permissions
• Performance: <30s added CI time

Definition of Done

• Validation step added to CI workflow
• Docs updated
• Demonstrated pass/fail behavior in PR

Estimated Effort

1 day