Persist pool-scoped grants using OR semantics across active provisions,
retaining lapsed rows for transition visibility. Add consumer queries,
DB-backed coverage, and plans for the dependent Discourse integration.
Add entitlement_sets and entitlement_set_rules with seed data and a
migration that backfills products, grants, and pool_provisions, then
removes product_entitlement_rules. Update Go models, sqlc queries,
materialization, and grant/provision flows to use entitlement_set_id.
Fix assembleMigrations to assign stable per-module numeric namespaces.
Move DB docs to docs/database-management.md and add design/specs/tests.
cgalo5758