Persist clone count to stats branch and update README badge

[Sendipad]

Motivation

• Ensure clone statistics are written to a dedicated stats folder on the stats branch for stable badge consumption.
• Make the repository README badges point to the persisted artifact on the stats branch instead of transient response files.

Description

• Updated .github/workflows/clone-stats.yml to save the GitHub API response to traffic.json, extract the count, create a stats directory, and write the final JSON to stats/clones.json before committing.
• Adjusted the commit step to git add stats/clones.json and push the stats branch.
• Updated README.md badges to reference the new raw file path on the stats branch (stats/stats/clones.json) and removed the old badge that pointed to develop.
• Added stats/README.md explaining how the stats branch artifacts are produced and where the badge reads the JSON from.

Testing

• No automated tests were modified or executed as part of this change.

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Codex Task