feat(billing): integrate Stripe for subscription management and billing access

- Added billing-related fields to the User model in the database.
- Implemented functions for managing billing access, including trial periods and subscription statuses.
- Created new billing utility functions for Stripe integration.
- Updated onboarding page to include billing overview and workspace creation eligibility.
- Enhanced route access checks to require billing access for certain actions.
- Implemented cleanup scripts for expired billing workspaces and associated media.
- Updated header component to conditionally show app navigation based on billing access.
- Added new migrations for billing-related database changes.

prisma/migrations/20260321003000_add_subscription_cancel_state/migration.sql

@@ -0,0 +1,3 @@
+ALTER TABLE "users"
+ADD COLUMN "stripeCancelAtPeriodEnd" BOOLEAN NOT NULL DEFAULT false,
+ADD COLUMN "stripeCancelAt" TIMESTAMP(3);