Use import aliases

**Is your feature request related to a problem? Please describe.**
Using too much `../../` in import statements is boring.

**Describe the solution you'd like**
Implement import alias `@/` instead of `../../` for better DX, maintaining and stability.

No files, tests, or entry points are named. Start by locating the repository's TypeScript and bundler configuration and inventorying relative imports using ../../; determine how an @/ alias would work across the React Native build and development setup. Done means the alias is configured consistently and existing imports can use it without breaking builds or platform behavior.

索引モデルが issue の本文から書いたものです。