fix(web): make OG image compatible with OpenNext

[willwashburn]

Summary

• switch the Open Graph image route from the Edge runtime to the Node.js runtime for OpenNext compatibility
• add the required explicit flex display on the multi-child heading block so the OG image prerenders during production builds
• fix the deploy job failure seen in Actions run 23367634365 / job 67984745247

Verification

• npm run build (in web/)

---

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 2 additional findings.