Replaces the single window.confirm() with a 3-stage wizard:
- preflight: counts auto/needs-reason/blocked (POST /bulk-archive-preflight)
- reasons: carousel through high-stakes clients capturing per-client
reason (≥5 chars) — bulk endpoint accepts reasonsByClientId map
- confirm: shows the final archivable count and submits
Low-stakes still auto-archives with safe defaults; blocked clients
are skipped with a per-row reason in the preflight summary.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>