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/@schematics/angular/e2e/schema.json

@@ -0,0 +1,20 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema",
+  "$id": "SchematicsAngularE2eApp",
+  "title": "Angular e2e Application Options Schema",
+  "type": "object",
+  "additionalProperties": false,
+  "description": "Generates a new, generic end-to-end test definition in the given project.",
+  "properties": {
+    "rootSelector": {
+      "description": "The HTML selector for the root component of the test app.",
+      "type": "string",
+      "default": "app-root"
+    },
+    "relatedAppName": {
+      "description": "The name of the application being tested.",
+      "type": "string"
+    }
+  },
+  "required": ["relatedAppName"]
+}