Investigate recurring CI issues and identify follow-up fixes

## Summary
Investigate the CI instability affecting the team and identify the highest-impact root causes.

## Goal
Produce a clear set of follow-up GitHub issues that capture specific, actionable fixes for the discovered CI problems.

## Scope
- Review recent CI failures and flaky jobs in this repository
- Identify recurring failure patterns, affected workflows, and likely root causes
- Propose concrete remediation work items as individual follow-up issues