Replace adv_status.sh with oca adv-status Go subcommand (O2)

[JRedeker]

Summary

lib/adv_status.sh (442 LOC, 15 shell functions) reads ADV internal state files with jq. Replace with oca adv-status Go subcommand that reads state through the advruntime package.

Why

• Shell reads of change.json, snapshot.json, temporal.env are fragile coupling to ADV internal format
• If ADV schema changes (signal cutover), shell parsing breaks silently
• Go subcommand is testable, typed, and degrades gracefully

Acceptance Criteria

• oca adv-status --format text replaces adv_status.sh output
• oca adv-status --format json for machine-readable output
• --query active-change|worktrees|temporal-health for specific queries
• adv_status.sh deleted or reduced to thin wrapper calling oca adv-status

Proposal

docs/proposals/2026-05-08-cross-repo-boundary-audit.md § O2 + § State File Reads

WSJF Estimate

Value: 8 | TC: 7 | RROE: 8 | Effort: 5 | WSJF: 4.6