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/cross-spawn/lib/util/escape.js

@@ -0,0 +1,47 @@
+'use strict';
+
+// See http://www.robvanderwoude.com/escapechars.php
+const metaCharsRegExp = /([()\][%!^"`<>&|;, *?])/g;
+
+function escapeCommand(arg) {
+    // Escape meta chars
+    arg = arg.replace(metaCharsRegExp, '^$1');
+
+    return arg;
+}
+
+function escapeArgument(arg, doubleEscapeMetaChars) {
+    // Convert to string
+    arg = `${arg}`;
+
+    // Algorithm below is based on https://qntm.org/cmd
+    // It's slightly altered to disable JS backtracking to avoid hanging on specially crafted input
+    // Please see https://github.com/moxystudio/node-cross-spawn/pull/160 for more information
+
+    // Sequence of backslashes followed by a double quote:
+    // double up all the backslashes and escape the double quote
+    arg = arg.replace(/(?=(\\+?)?)\1"/g, '$1$1\\"');
+
+    // Sequence of backslashes followed by the end of the string
+    // (which will become a double quote later):
+    // double up all the backslashes
+    arg = arg.replace(/(?=(\\+?)?)\1$/, '$1$1');
+
+    // All other backslashes occur literally
+
+    // Quote the whole thing:
+    arg = `"${arg}"`;
+
+    // Escape meta chars
+    arg = arg.replace(metaCharsRegExp, '^$1');
+
+    // Double escape meta chars if necessary
+    if (doubleEscapeMetaChars) {
+        arg = arg.replace(metaCharsRegExp, '^$1');
+    }
+
+    return arg;
+}
+
+module.exports.command = escapeCommand;
+module.exports.argument = escapeArgument;