feat!: switch to native ESM with NodeNext module resolution and .js import paths

BREAKING CHANGE: Consumers must use ESM-compatible environments.
All import paths now include .js extensions.
CommonJS (require) is no longer supported.

src/interfaces/Exceptions.ts

@@ -1,5 +1,5 @@
-import { Identifier } from 'src/types/Identifier';
-import { ITSinjex } from './ITSinjex';
+import { Identifier } from 'src/types/Identifier.js';
+import { ITSinjex } from './ITSinjex.js';
 
 /**
  * General error class for {@link ITSinjex} interface.

src/interfaces/ITSinjex.ts

@@ -1,5 +1,5 @@
-import { DependencyResolutionError } from './Exceptions';
-import { Identifier } from '../types/Identifier';
+import { DependencyResolutionError } from './Exceptions.js';
+import { Identifier } from '../types/Identifier.js';
 
 /**
  * Static TSInjex Interface