CLN-04: Replaced any with unknown, proper interfaces, or concrete
types across 17 files. Focus: error handlers, API responses,
WebSocket data, and function parameters.
- Replace manual ApiError interface with Zod-inferred type from apiSchemas
- Update all imports (15+ files) to use ApiError from @/schemas/apiSchemas
- Remove ApiError interface from types/api.ts
- Update ApiResponse to import ApiError from schemas
- All TypeScript checks pass for ApiError-related code