Add admin APIs to list/create/invalidate/delete user subscriptions
Add model helpers to fetch all user subscriptions (incl. expired) and support cancel/hard-delete
Wire new admin routes for user subscription operations
Replace “Bind subscription plan” entry with a dedicated User Subscriptions SideSheet in Users table
Use CardTable with responsive layout and working client-side pagination inside the SideSheet
Improve subscription purchase modal empty-gateway state with a Banner notice