Add TypeScript strict mode and fix type errors

Description

Enable TypeScript strict mode to catch more bugs at compile time and improve code quality.

Current State

Many components have any types and implicit type coercion that could lead to runtime errors.

Tasks

• Enable strict mode in tsconfig.json
• Fix all type errors in components/
• Fix all type errors in utils/
• Add proper types to API response interfaces
• Remove all any types

cc @michael @stan