Typegen produces result: unknown when warehouse query fails

[jamesbroadhead]

Summary

When appkit generate-types fails to execute a query against the warehouse (e.g. format incompatibility, stale session), it generates result: unknown in appKitTypes.d.ts instead of failing the build. This causes TypeScript compilation errors in components that depend on the generated types (Property 'length' does not exist on type '{}').

Reproduction

1. Have a query file revenue_by_destination.sql in config/queries/
2. The warehouse rejects the typegen query (format error, session timeout, etc.)
3. Typegen shows ✓ revenue_by_destination (success!) but generates: result: unknown
4. tsc fails because components expect data to be an array

Expected behavior

Either:

• Typegen should fail the build when it can't determine result types
• Or typegen should preserve the previous good types instead of overwriting with unknown
• At minimum, typegen should show ✗ (failure) when it produces unknown types