#16 1-9

fix: complete story 1.9 seed defaults Seed system reference values, readiness required-field rules, and overdue milestone escalation defaults during application startup. Add idempotent seed-key storage with source metadata so reruns avoid duplicates and preserve admin-managed values. Replace the corrupted seed test file with coverage for first seed, persistence, idempotency, FR29 readiness scope, FR30 escalation defaults, and admin override preservation.