Refactor executable IDs to use strings #262

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.

docs/collection-files.md

@@ -30,6 +30,8 @@ Related documentation:
 
 ### Executables
 
+They represent independently executable actions with documentation and reversibility.
+
 An Executable is a logical entity that can
 
 - execute once compiled,