fix(dates): enforce 'en-US' locale for date formatting in rss.ts and repoSpotlight.ts

[ChetanSenta]

Description

Fixes #9015

Pillar

• 🎨 Pillar 1 — New Theme Design
• 📐 Pillar 2 — Geometric SVG Improvement
• 🕐 Pillar 3 — Timezone Logic Optimization
• 🛠️ Other

What this PR does

lib/rss.ts and lib/svg/repoSpotlight.ts both called
toLocaleDateString(undefined, ...), letting the server's ambient
runtime locale determine the date format baked into the generated SVG
badge — a real risk given how commonly minimal Node.js Docker builds
ship reduced ICU data. lib/github.ts's joinedDate formatting already
correctly pins this to 'en-US' — applied the same fix to the two
outliers.

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file.
• I have tested these changes locally.
• I have run npm run format and npm run lint locally and resolved all errors.
• My commits follow the Conventional Commits format.
• I have made sure that I have only one commit to merge in this PR.

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[retenta-bot]

This pull request addresses issue #9015 by pinning the date formatting to the 'en-US' locale in two files, which helps avoid potential inconsistencies in date representation due to varying server locales. This approach is similar to previous decisions made regarding badge URL extraction logic, where consistency and reliability were prioritized. Thank you for your contribution!

[Aamod007]

The fix for pinning the locale to 'en-US'\ in \lib/rss.ts\ and
epoSpotlight.ts\ is absolutely correct and a great catch to ensure deterministic SVG generation regardless of the server's ambient locale!

However, it looks like this PR unintentionally reverts the recent timezone testing fix from PR #8994 in \utils/dateHelpers.test.ts. You re-added the 'Z'\ to the test timestamps, which will cause those tests to fail or act inconsistently in non-UTC environments again.

Could you please revert the changes to \utils/dateHelpers.test.ts\ so we keep the timezone fix intact? Once that's removed, I'll be happy to approve this!

[github-actions]

📦 Next.js Bundle Size Report (Gzipped Sizes)

✨ No significant bundle size changes detected.

📊 Summary of Totals

Category	PR Size	Base Size	Difference
Total JS	5004.32 KB	5004.32 KB	0 B
Total CSS	354.80 KB	354.80 KB	0 B

[Aamod007]

Thanks for resolving the regression on the timestamp strings in \dateHelpers.test.ts! The fix for pinning the locale to \en-US\ is a very solid consistency improvement for the SVGs across different Node.js execution environments.

Approved!

[github-actions]

⚠️ Hey @ChetanSenta, this pull request has been inactive for 3 days. It will be automatically closed in 2 days if no further activity occurs.

If you are still working on this, please push your latest changes or leave a comment to keep it active.