Add per-endpoint circuit breaker for downstream calls on /api/comments [b#039]

[greatest0fallt1me]

Description

This is a backend issue for the GrantFox FWC26 campaign. Circuit breaker around downstream calls made by /api/comments; 503 fast on open.

Requirements and Context

• Implement per the description above
• Add focused tests for the change
• Document any API/visible changes
• Adhere to repo's lint and code style
• Must be secure, tested, and documented

Suggested Execution

1. Fork the repo and create a branch
2. Implement changes touching:
   • src/routes/comments.ts
   • src/lib/circuitBreaker.ts
3. Test and commit; open a PR with Closes #<issue-number> in the body

Guidelines

• Minimum 90% test coverage on changed lines
• Input validation at the boundary; standardized error envelope
• Structured logging with correlation IDs
• Clear documentation and inline comments
• Timeframe: 96 hours

[thelmaoffiong]

@thelmaoffiong has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi maintainer i would love to work on this issue. Thanks

ℹ️ Repo Maintainers: To accept this application, review their application or assign @thelmaoffiong to this issue.

[drips-wave]

Congratulations, @thelmaoffiong! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @thelmaoffiong: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[greatest0fallt1me]

@thelmaoffiong you're in — this issue is yours. Join the community on Discord: https://discord.gg/WC53JxDqx

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@thelmaoffiong's PR #724 was approved and merged by @greatest0fallt1me.

🏆 @thelmaoffiong: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (293 total points). Track your full progress on GrantFox.

👏 Great work, @thelmaoffiong! Keep contributing to Predictify-org.

[drips-wave]

This issue has been completed by @thelmaoffiong as part of the Stellar Wave Program's 7th Wave 🥳

😎 @thelmaoffiong: You earned 100 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.