Add per-endpoint metrics on /api/auth (v7)

[greatest0fallt1me]

Description

This is a backend issue for the GrantFox campaign. This is a backend issue for the GrantFox FWC26 campaign (Stellar Wave). Prometheus histogram/counter on /api/auth.

Requirements and Context

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

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b task/auth-metrics-v7

2. Implement changes
   • src/routes/auth.ts
   • src/metrics/registry.ts
3. Test and commit
   • Run the repo's standard test suite and lint
   • Cover edge cases; include output in the PR

Example commit message

feat: metrics on /api/auth

Acceptance Criteria

• Implementation matches the description
• Tests added and passing
• Code review approved
• Docs updated

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

[miriamisa022-cyber]

@miriamisa022-cyber has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi! I'm interested in working on this issue. If no one else is currently working on it, I'd be happy to take it on. Could you please assign it to me?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @miriamisa022-cyber to this issue.

[greatest0fallt1me]

Hey @miriamisa022-cyber 👋 — you've been assigned to this issue based on your DripsWave application.

Quick reminders:

• Draft PR early and link it with Closes #<issue-number> so the DripsWave bot auto-closes.
• Please respect the 4 assignments per org cap (DripsWave auto-unassigns beyond that).
• Ping in Discord for questions or unblocks: https://discord.gg/WC53JxDqx

Looking forward to your PR — good luck! 🚀

[drips-wave]

Congratulations, @miriamisa022-cyber! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @miriamisa022-cyber: 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 🌊