Add GitHub Action to track repository clone traffic

[dave3d]

Adds a daily scheduled workflow (.github/workflows/track-clones.yml) that:

• Calls the GitHub Traffic API to fetch clone statistics
• Accumulates daily records in .github/clone-traffic.json, deduplicating by timestamp
• Commits updated data back to the repo with [skip ci]

Setup required: Add a PAT with repo traffic read access as a repository secret named TRAFFIC_TOKEN.