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/@isaacs/cliui/index.mjs

@@ -0,0 +1,14 @@
+// Bootstrap cliui with ESM dependencies:
+import { cliui } from './build/lib/index.js'
+
+import stringWidth from 'string-width'
+import stripAnsi from 'strip-ansi'
+import wrap from 'wrap-ansi'
+
+export default function ui (opts) {
+  return cliui(opts, {
+    stringWidth,
+    stripAnsi,
+    wrap
+  })
+}