Introduces ai_points_monthly and ai_point_base_chars on the membership
plan policy, exposes them through TenantPlanAccess and MembershipInfo,
and seeds Pro with a 1500-point monthly allowance across the local,
server, and deploy configs.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Add configurable membership plans (free/plus/pro) synced to DB on boot, a
subscription guard middleware that blocks tenant endpoints on expired or
missing plans, and a MembershipBlockedView that surfaces the reason so
the admin can contact the tenant owner. Quota and brand-library reads now
honor the active plan's policy JSON and expired subscriptions.