Type safety audit and improvements

[wheelsandcogs]

Overview

Audit and improve TypeScript type safety across the backend codebase.

Tasks

• Audit for any any type usage and replace with proper types
• Review and strengthen interface definitions
• Add stricter TypeScript compiler options if appropriate
• Ensure all function parameters and return types are explicitly typed
• Add type guards where runtime type checking is needed
• Review and type external API responses
• Document complex types with JSDoc comments

Acceptance Criteria

• No unnecessary any types in the codebase
• All public functions have explicit return types
• External data is properly validated and typed
• TypeScript strict mode passes (or document exceptions)
• Complex types are documented

Related

Part of Phase 5: Code Quality Improvements for code quality improvement initiative.