feat: implement issue #1997 — Lower the advisory quorum to 5: drop the three reviewers that produce no countable signal (re-file of #1894 AC #3)
Problem
Lower the advisory quorum to 5: drop the three reviewers that produce no countable signal (re-file of #1894 AC #3)
From the issue: As the fleet operator, I want the advisory quorum to count only reviewers that actually produce a countable signal, so that pr-review stops reaching approval through a timeout fallback on every single PR.
Risk
Low — changes automation shell logic under scripts/, covered by shellcheck (--severity=warning) and the bats suite.
Test plan
Tests added/updated: tests/dev-lead/unit/test_advisory_review_gate.bats,tests/test_reviewer_sources.bats. Verification: bash scripts/dev-lead-lint.sh (shellcheck --severity=warning) ran pre-commit; the bats suite runs in CI.
Rollback
Revert this PR. No non-revertible side effects (no tags, migrations, or external state).
Monitoring
This PR's Lint (shellcheck) and bats checks show pass/fail; watch subsequent dev-lead / pr-review runs for behavioral regressions.
Closes #1997