Refactor to unify scripts/categories as Executable

This commit consolidates scripts and categories under a unified
'Executable' concept. This simplifies the architecture and improves code
readability.

- Introduce subfolders within `src/domain` to segregate domain elements.
- Update class and interface names by removing the 'I' prefix in
  alignment with new coding standards.
- Replace 'Node' with 'Executable' to clarify usage; reserve 'Node'
  exclusively for the UI's tree component.

tests/unit/shared/Stubs/ScriptStub.ts

@@ -1,13 +1,13 @@
 import { BaseEntity } from '@/infrastructure/Entity/BaseEntity';
-import type { IScript } from '@/domain/IScript';
-import { RecommendationLevel } from '@/domain/RecommendationLevel';
-import type { IScriptCode } from '@/domain/IScriptCode';
+import type { Script } from '@/domain/Executables/Script/Script';
+import { RecommendationLevel } from '@/domain/Executables/Script/RecommendationLevel';
+import type { ScriptCode } from '@/domain/Executables/Script/Code/ScriptCode';
 import { SelectedScriptStub } from './SelectedScriptStub';
 
-export class ScriptStub extends BaseEntity<string> implements IScript {
+export class ScriptStub extends BaseEntity<string> implements Script {
   public name = `name${this.id}`;
 
-  public code: IScriptCode = {
+  public code: ScriptCode = {
     execute: `REM execute-code (${this.id})`,
     revert: `REM revert-code (${this.id})`,
   };