chore(site): update analytics to new GTM container + GA4

[oceans404]

What

Updates the analytics tags on skills.stellar.org per Alexis (marketing).

• Replaces GTM container GTM-KCNDDL3 → GTM-KPV99TKH
• Adds GA4 (G-6PQ8C6FJSR) via @next/third-parties's GoogleAnalytics

Both load through the framework components (equivalent to the raw GTM/GA4 snippets) and stay behind the existing production-only GA_TRACKING_ENABLED gate, so nothing fires on localhost or PR previews.

Note / open question

The site now loads GTM and GA4 directly. If the GTM-KPV99TKH container is also configured to fire a GA4 tag for G-6PQ8C6FJSR, pageviews will be double-counted. Confirming intended setup with marketing; may follow up with a tweak to fire GA4 from only one source.

Testing

• GTM-KCNDDL3 fully removed; only the two new IDs remain in site/
• Not yet run locally (node_modules not installed in this checkout): please run pnpm lint:ts, pnpm lint, pnpm build before merge

🤖 Generated with Claude Code

[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-07-16 17:46 UTC

[Copilot]

Pull request overview

Updates site analytics by replacing the GTM container and adding direct GA4 tracking behind the existing production-only gate.

Changes:

• Replaces the existing GTM container ID.
• Adds GA4 through GoogleAnalytics.

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[jeesunikim]

According to NextJS' https://nextjs.org/docs/app/guides/third-party-libraries#google-analytics:

Recommendation: If Google Tag Manager is already included in your application, you can configure Google Analytics directly using it, rather than including Google Analytics as a separate component. Refer to the documentation to learn more about the differences between Tag Manager and gtag.js.

Can we check to see if GA4 tracking is already configured in GTM? If so, this change can double count events.

[oceans404]

According to NextJS' https://nextjs.org/docs/app/guides/third-party-libraries#google-analytics:

Recommendation: If Google Tag Manager is already included in your application, you can configure Google Analytics directly using it, rather than including Google Analytics as a separate component. Refer to the documentation to learn more about the differences between Tag Manager and gtag.js.

Can we check to see if GA4 tracking is already configured in GTM? If so, this change can double count events.

Alexis from marketing asked us to keep it this way for now - docs is configured this way too and I think they dedupe on their side. I'll follow up with her about both docs and skills tracking