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/@npmcli/git/lib/which.js

@@ -0,0 +1,18 @@
+const which = require('which')
+
+let gitPath
+try {
+  gitPath = which.sync('git')
+} catch {
+  // ignore errors
+}
+
+module.exports = (opts = {}) => {
+  if (opts.git) {
+    return opts.git
+  }
+  if (!gitPath || opts.git === false) {
+    return Object.assign(new Error('No git binary found in $PATH'), { code: 'ENOGIT' })
+  }
+  return gitPath
+}