fix(nuxthub): use generated schema

[onmax]

Summary

• Use the module-generated Drizzle schema for the NuxtHub database provider (instead of @nuxthub/db exported schema).
• Fail fast when schema generation fails to avoid runtime 500s.

Tests

• pnpm vitest run test/nuxthub-otp-workaround.test.ts

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/nuxt-modules/better-auth/@onmax/nuxt-better-auth@156

commit: 28f1d7d