Initial commit: notification-elements-demo app

Interactive Angular 19 demo for @sda/notification-elements-ui with
6 sections: Bell & Feed, Notification Center, Inbox, Comments &
Threads, Mention Input, and Full-Featured layout. Includes mock
data, dark mode toggle, and real-time event log.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

node_modules/@tufjs/models/dist/signature.d.ts

@@ -0,0 +1,20 @@
+import { JSONObject } from './utils';
+export interface SignatureOptions {
+    keyID: string;
+    sig: string;
+}
+/**
+ * A container class containing information about a signature.
+ *
+ * Contains a signature and the keyid uniquely identifying the key used
+ * to generate the signature.
+ *
+ * Provide a `fromJSON` method to create a Signature from a JSON object.
+ */
+export declare class Signature {
+    readonly keyID: string;
+    readonly sig: string;
+    constructor(options: SignatureOptions);
+    toJSON(): JSONObject;
+    static fromJSON(data: JSONObject): Signature;
+}