Encrypted sync gets a dedicated data plane

CurbApps now has a clearer split between account data and product data.

Supabase handles authentication, accounts, subscriptions, and billing. The sync Worker stores encrypted application records in Cloudflare D1 and encrypted files in R2.

CurbPage, CurbPlace, CurbTube, CurbTime, the web dashboard, and the mobile companion all use the same scoped sync contract. Record contents are encrypted on the client before they leave the device.

The latest D1 migration also makes record identity scope-safe, so the same client-generated ID can exist in separate data scopes without colliding.