commercial-legal renewal-tracker: contradictory alert date (send_by vs cancel_by), stale schema field, and undefined --horizon flag #122

Contradictions in renewal-tracker/SKILL.md

• Line 80: urgency bands fire off send_by_effective ("not cancel_by_effective").
• Line 101: urgency bands use cancel_by_effective.
• The reference schema still uses a single cancel_by field (references/renewal-register.yaml:18) while the skill defines cancel_by_calendar / cancel_by_effective / send_by_effective (:66-68).
• Line 120 references --horizon, but the only documented flag is --days N (:9, :22).

Why it matters

With a certified-mail notice clause, alerting off cancel_by instead of send_by can put a 🔴 alert after the last day notice could actually be sent. The model gets to pick either rule depending on which line it weights.

Proposed fix

Cheap: change line 101 to send_by_effective (matching line 80), update the reference YAML to the three-field schema, replace --horizon with --days.