feat(core): Add new matchers and improve negation messaging

ts/index.ts

@@ -1,4 +1,4 @@
-import { Assertion } from './smartexpect.classes.assertion.js';
+import { Assertion, AnyMatcher, AnythingMatcher } from './smartexpect.classes.assertion.js';
 // import type { TMatcher } from './smartexpect.classes.assertion.js'; // unused
 
 /**
@@ -24,6 +24,18 @@ export function expect<T>(value: any): Assertion<T> {
  */
 export namespace expect {
   export const extend = Assertion.extend;
+  /**
+   * Matcher for a specific constructor. Passes if value is instance of given constructor.
+   */
+  export function any(constructor: any) {
+    return new AnyMatcher(constructor);
+  }
+  /**
+   * Matcher for any defined value (not null or undefined).
+   */
+  export function anything() {
+    return new AnythingMatcher();
+  }
 }
 
 /**