Remove informational workflow comments that cascade into extra Actions runs

[Mpfk]

Summary

Follow-up to #149. Issue/PR comments posted by automation workflows are themselves issue events, which trigger issue-state-guard.yml and potentially issue-native-automation.yml — adding cascading runs for every status transition. The comments are also redundant: agents and developers can observe the same information through labels, CI check status, and branch existence directly.

Description

Remove informational comment-posting from two workflows:

ci-issue-gate.yml

• Remove: CI failure comment ("Gate check failed: CI checks are not green…")
• Remove: CI pass comment ("Review kickoff: CI checks are green…")
• Keep: setStatus() label transitions (these are the real work)

issue-native-automation.yml

• Remove: "Issue is ready. Branch ready: issue/N. Assign to Copilot…" (branch existence is observable)
• Remove: "Implementation kickoff:" block (content lives in .github/copilot-instructions.md)
• Remove: "Gate 1 approved by @Actor…" confirmation (label transition to status/ready is observable)
• Keep: error-guard comments ("Copilot assignment detected, but issue is not status/ready", "Plan approval command ignored:") — these signal misconfiguration and are not routine

Acceptance Criteria

• ci-issue-gate.yml no longer posts any createComment calls; label transitions (setStatus) are unchanged
• issue-native-automation.yml drops the three informational comments but retains the two error-guard comments
• tests/workflow-config.sh passes with no regressions (all existing assertions green)

[github-actions]

Review kickoff: CI checks are green on the draft PR. Status moved to status/review.

Next:

• Invoke Copilot 'review' Agent and confirm PASS.
• Keep PR as draft until Gate 2 prerequisites are satisfied.
• After PASS, convert PR to ready-for-review and proceed to Gate 2 merge approval.

[github-actions]

Gate 2 complete: PR merged. Status moved to status/done. Next step: no action required unless follow-up work is needed.