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/side-channel-map/index.d.ts

@@ -0,0 +1,15 @@
+declare namespace getSideChannelMap {
+	type Channel<K, V> = {
+		assert: (key: K) => void;
+		has: (key: K) => boolean;
+		get: (key: K) => V | undefined;
+		set: (key: K, value: V) => void;
+		delete: (key: K) => boolean;
+	};
+}
+
+declare function getSideChannelMap<K, V>(): getSideChannelMap.Channel<K, V>;
+
+declare const x: false | typeof getSideChannelMap;
+
+export = x;