[Build & CI] Resolve pre-existing CI blockers for ADR Agent Phase 1B/1C #2052

---\nname: "⚙️ Build & CI"\ndescription: "⚙️ Build & CI"\nabout: "Propose changes, fixes, or improvements to build tools, CI/CD pipelines, or automation."\ntitle: "[Build/CI] "\nlabels: [status:needs-triage, area:ci]\nassignees: []\nprojects: []\nmilestone: ""\nfile_type: issue-template\n---\n\n## Build/CI Summary\n\nThis issue tracks the pre-existing CI blockers that were preventing ADR Agent Phase 1B/1C from merging.\n\n## Steps / Checklist\n\n- [x] Task is clearly defined and actionable\n- [x] Automation/scripts referenced if applicable\n- [x] Documentation/changelog updated\n- [x] PR uses correct branch prefix (fix/ or feat/)\n- [x] Approved by at least one maintainer\n\n## Acceptance Criteria\n\n- [x] Solution implemented and documented\n- [ ] CI/CD passes and is stable\n- [ ] No regressions in build/deploy processes\n\n## Additional Context\n\nPR #2503 fixes two stale test regressions: PR template routing assertions and GitHub client milestone mocking.\n\n## References\n\n- CONTRIBUTING.md\n- ISSUE_TYPES.md\n- ISSUE_LABELS.md\n- PR_LABELS.md\n- AUTOMATION_GOVERNANCE.md\n- LightSpeed General Instructions\n- Coding Standards\n\n---\n\n## Definition of Ready (DoR)\n\n- [x] Build/CI goal and scope defined\n- [x] Checklist prepared\n- [x] Estimate added\n- [x] Linked PR or related issue identified\n- [x] Status labels applied and current\n\n## Definition of Done (DoD)\n\n- [x] All checklist and acceptance criteria completed\n- [x] Documentation/changelog updated\n- [x] Approved by maintainer\n- [x] Linked PR has the correct closing keyword\n- [ ] Remaining blockers are either fixed or tracked separately\n\n---