fix: code review cleanup

- Replace all 'any' types with proper Prisma types
- Fix exactOptionalPropertyTypes compatibility
- Export AuthUser type from better-auth-request.interface
- Remove duplicate empty migration folder
- Ensure proper JSON handling with Prisma.InputJsonValue

All agent-tasks tests passing (18/18)

apps/api/src/auth/types/better-auth-request.interface.ts

@@ -8,6 +8,9 @@
 
 import type { AuthUser } from "@mosaic/shared";
 
+// Re-export AuthUser for use in other modules
+export type { AuthUser };
+
 /**
  * Session data stored in request after authentication
  */