feat: publish secure dynamic repository metrics

[JNHFlow21]

Summary

• replace the restricted Star History embed with a repository-owned white sketch-style SVG
• refresh stars, forks, commits, visitors, cloners, and clone totals using GitHub Actions
• publish generated output on an orphan metrics branch without embedding a long-lived token
• add renderer and README contract tests

Validation

• PYTHONPATH=src python3 -m unittest discover -s tests -v (77 passed)
• python3 scripts/privacy_scan.py
• actionlint .github/workflows/repository-metrics.yml
• local live-data SVG render and visual review

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Supply a token permitted to read repository traffic

The workflow GITHUB_TOKEN can only receive the permissions exposed under permissions:, and contents: write does not grant the Administration (read) permission required by the /traffic/views and /traffic/clones endpoints called by fetch_snapshot(). Consequently, every watch, scheduled, or manual run reaches those calls with ${{ github.token }} and receives a 403 before generating or publishing the SVG; use a GitHub App or other credential with repository traffic access, keeping the branch-push credential separate if necessary.

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