Improve dataset repo presentability

[shaypal5]

Summary

• Add a repository-root MIT LICENSE so GitHub and first-time users can detect reuse terms without opening a release subdirectory.
• Improve the README landing experience with status badges, explicit license/reuse guidance, and a compact preview of the public intro/lead_scoring.csv shape.
• Add lightweight CI that validates the committed alpha release structure, public flat-file contract, and redaction expectations.
• Update the changelog with the presentability and validation improvements.

Why

The presentability review for the 28-repo working set flagged leadforge-dev/leadforge-datasets as the first repo to treat because it is a public dataset repository with no root license metadata and a useful but under-packaged first impression. The release bundle already carried an MIT license copy, so this PR promotes that existing license posture to the repository root and makes the public-facing README more self-contained.

Impact

• GitHub should classify the repository license after this lands on main.
• New visitors can see what the dataset looks like before cloning or opening large files.
• CI now catches accidental release-structure regressions without requiring the full leadforge generator stack.
• Dataset contents are unchanged.

Validation

• python3 scripts/validate_release.py
• python3 -m py_compile scripts/validate_release.py
• git diff --check

GitHub settings completed

• Description: Public synthetic CRM and lead-scoring dataset bundles generated by leadforge.
• Homepage: https://leadforge-dev.github.io/leadforge/
• Topics: crm, dataset, lead-scoring, sales-analytics, synthetic-data, teaching-data

Milestone

No repository milestones currently exist, so no milestone was assigned.