This commit unifies executable ID structure across categories and
scripts, paving the way for more complex ID solutions for #262.
It also refactors related code to adapt to the changes.
Key changes:
- Change numeric IDs to string IDs for categories
- Use named types for string IDs to improve code clarity
- Add unit tests to verify ID uniqueness
Other supporting changes:
- Separate concerns in entities for data access and executables by using
separate abstractions (`Identifiable` and `RepositoryEntity`)
- Simplify usage and construction of entities.
- Remove `BaseEntity` for simplicity.
- Move creation of categories/scripts to domain layer
- Refactor CategoryCollection for better validation logic isolation
- Rename some categories to keep the names (used as pseudo-IDs) unique
on Windows.