[ci] Add code coverage reporting with enforced minimum threshold (80%)

[CelestinaBeing]

Context

Coverage is uploaded to Codecov but there is no enforced minimum threshold. PRs that drop coverage below 80% should be flagged.

Work

• Add a Codecov config at codecov.yml with coverage.status.patch.target: 80%
• Add coverage.status.project.target: 80% for overall
• Configure Codecov to comment on PRs with coverage delta
• Investigate and fix any existing coverage gaps

Acceptance criteria

• Codecov PR check fails if patch coverage < 80%
• Coverage comment posted on every PR
• Overall coverage ≥ 80% on main branch

[intelliDean]

@intelliDean has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I'd like to work on this issue

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

[Rampop01]

@Rampop01 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue . I understand the assignment and the requirements, and I’m confident in the approach needed to deliver the best solution. Kindly assign this task to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Rampop01 to this issue.

[drips-wave]

Congratulations, @Rampop01! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @Rampop01: 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 🌊