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.

tests/unit/shared/Stubs/CategoryCollectionValidationContextStub.ts

@@ -0,0 +1,34 @@
+import type { CategoryCollectionValidationContext } from '@/domain/Collection/Validation/CategoryCollectionValidator';
+import type { Category } from '@/domain/Executables/Category/Category';
+import type { Script } from '@/domain/Executables/Script/Script';
+import { OperatingSystem } from '@/domain/OperatingSystem';
+import { CategoryStub } from './CategoryStub';
+import { ScriptStub } from './ScriptStub';
+
+export class CategoryCollectionValidationContextStub
+implements CategoryCollectionValidationContext {
+  public allScripts: readonly Script[] = [
+    new ScriptStub(`[${CategoryCollectionValidationContextStub.name}] test-script`),
+  ];
+
+  public allCategories: readonly Category[] = [
+    new CategoryStub(`[${CategoryCollectionValidationContextStub.name}] test-category`),
+  ];
+
+  public operatingSystem: OperatingSystem = OperatingSystem.iPadOS;
+
+  public withOperatingSystem(operatingSystem: OperatingSystem): this {
+    this.operatingSystem = operatingSystem;
+    return this;
+  }
+
+  public withAllCategories(allCategories: readonly Category[]): this {
+    this.allCategories = allCategories;
+    return this;
+  }
+
+  public withAllScripts(allScripts: readonly Script[]): this {
+    this.allScripts = allScripts;
+    return this;
+  }
+}