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/negotiator/package.json

@@ -0,0 +1,43 @@
+{
+  "name": "negotiator",
+  "description": "HTTP content negotiation",
+  "version": "1.0.0",
+  "contributors": [
+    "Douglas Christopher Wilson <doug@somethingdoug.com>",
+    "Federico Romero <federico.romero@outboxlabs.com>",
+    "Isaac Z. Schlueter <i@izs.me> (http://blog.izs.me/)"
+  ],
+  "license": "MIT",
+  "keywords": [
+    "http",
+    "content negotiation",
+    "accept",
+    "accept-language",
+    "accept-encoding",
+    "accept-charset"
+  ],
+  "repository": "jshttp/negotiator",
+  "devDependencies": {
+    "eslint": "7.32.0",
+    "eslint-plugin-markdown": "2.2.1",
+    "mocha": "9.1.3",
+    "nyc": "15.1.0"
+  },
+  "files": [
+    "lib/",
+    "HISTORY.md",
+    "LICENSE",
+    "index.js",
+    "README.md"
+  ],
+  "engines": {
+    "node": ">= 0.6"
+  },
+  "scripts": {
+    "lint": "eslint .",
+    "test": "mocha --reporter spec --check-leaks --bail test/",
+    "test:debug": "mocha --reporter spec --check-leaks --inspect --inspect-brk test/",
+    "test-ci": "nyc --reporter=lcov --reporter=text npm test",
+    "test-cov": "nyc --reporter=html --reporter=text npm test"
+  }
+}