Add default_plan_ladder_id with a forward data migration and update
the runtime to resolve the ladder's rank-0 tier at use-time. Regenerate
sqlc, update auto-provisioning, ReapplyDefaultsForPool, operator UI and
tests; add GetTierByLadderRank and pool/provision query helpers. Add a
CSP-safe confirm-action modal and wire operator actions to it. Close
plan-sole-writer safety gaps and serialize IssueGrant with a FOR UPDATE
pool lock to prevent ladder races.