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.

src/application/Parser/Executable/Script/Validation/Syntax/ShellScriptSyntax.ts

@@ -0,0 +1,7 @@
+import type { ILanguageSyntax } from '@/application/Parser/Executable/Script/Validation/Syntax/ILanguageSyntax';
+
+export class ShellScriptSyntax implements ILanguageSyntax {
+  public readonly commentDelimiters = ['#'];
+
+  public readonly commonCodeParts = ['(', ')', 'else', 'fi', 'done'];
+}