fix(readme): restore broken star history chart

[FaintFlower]

The star history chart in the README stopped working, which makes the repository look stale to visitors. This PR replaces it with a working alternative so the chart renders again.

No other changes are included.

[vercel]

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: c5b351c5-4aaf-40ba-9116-b06a05be15f1

📥 Commits

Reviewing files that changed from the base of the PR and between fc14a4a and 3d54471.

📒 Files selected for processing (1)

• README.md

Included review availability: Your plan includes up to 4 reviews per rolling hour; 3 remain after this review.

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📝 Walkthrough

Walkthrough

The README Star History link and chart image sources now use the star-history.dera.page domain.

Changes

Star History Embed

Layer / File(s)	Summary
Update Star History URLs README.md	The Star History link and chart image sources now use star-history.dera.page URLs.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to 3d544

This PR only restores the README star history chart and does not change application behavior; no actionable merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes restoring the broken Star History chart in the README.
Description check	✅ Passed	The description accurately explains the broken chart, the replacement, and the absence of other changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests

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