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/call-bind-apply-helpers/applyBind.d.ts

@@ -0,0 +1,19 @@
+import actualApply from './actualApply';
+
+type TupleSplitHead<T extends any[], N extends number> = T['length'] extends N
+  ? T
+  : T extends [...infer R, any]
+  ? TupleSplitHead<R, N>
+  : never
+
+type TupleSplitTail<T, N extends number, O extends any[] = []> = O['length'] extends N
+  ? T
+  : T extends [infer F, ...infer R]
+  ? TupleSplitTail<[...R], N, [...O, F]>
+  : never
+
+type TupleSplit<T extends any[], N extends number> = [TupleSplitHead<T, N>, TupleSplitTail<T, N>]
+
+declare function applyBind(...args: TupleSplit<Parameters<typeof actualApply>, 2>[1]): ReturnType<typeof actualApply>;
+
+export = applyBind;