- Create Account model as Cashier Billable entity (stripe, plan, subscription)
- Account owns workspaces and has an owner_id (User)
- User belongs to one Account via account_id
- Workspace belongs to Account via account_id, no longer has billing fields
- Remove Brand model entirely (workspaces serve as grouping)
- Rename brand_limit to workspace_limit in plans
- Workspace roles simplified: admin/member/viewer (owner via Account)
- Invites now belong to Account with workspaces JSON array
- Pennant features scope changed from Workspace to Account
- EnsureSubscribed middleware checks Account subscription
- All controllers updated: BillingController, OnboardingController,
WorkspaceInviteController, SocialController, StripeEventListener
- Frontend: extract GoogleAuthButton component, create WorkspaceRole
enum for type-safe role checks, fix all views for new architecture
- All 1101 tests passing
