Fix Star History with token-free daily snapshots

[Maple127667]

Summary

• replace the restricted stargazer-list request and persistent PAT with one daily aggregate stargazers_count snapshot
• render the chart in a read-only job, then publish only star-history.json and star-history.svg to the dedicated star-history branch
• point both README variants at the generated branch and remove the stale checked-in SVG
• seed the aggregate-only history so the chart retains its existing trend

Security boundaries

• no personal access token or repository secret
• no stargazer usernames, profiles, or individual timestamps are collected
• the renderer receives only the run-scoped read-only GITHUB_TOKEN
• write permission exists only in the publish job and targets the star-history output branch
• third-party workflow actions are pinned to full commit SHAs

Validation

• Python compilation, JSON/YAML parsing, deterministic render, and live public-metadata render passed locally
• end-to-end workflow run succeeded: https://github.com/Roboparty/roboto_origin/actions/runs/31575182992
• the generated branch contains exactly star-history.json and star-history.svg
• latest snapshot: 2026-08-12, 2207 stars

Existing dev content

Because this PR intentionally uses the repository's existing dev branch, it also includes the earlier license-scope clarification already present on dev before this fix.