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/make-fetch-happen/lib/pipeline.js

@@ -0,0 +1,41 @@
+'use strict'
+
+const MinipassPipeline = require('minipass-pipeline')
+
+class CachingMinipassPipeline extends MinipassPipeline {
+  #events = []
+  #data = new Map()
+
+  constructor (opts, ...streams) {
+    // CRITICAL: do NOT pass the streams to the call to super(), this will start
+    // the flow of data and potentially cause the events we need to catch to emit
+    // before we've finished our own setup. instead we call super() with no args,
+    // finish our setup, and then push the streams into ourselves to start the
+    // data flow
+    super()
+    this.#events = opts.events
+
+    /* istanbul ignore next - coverage disabled because this is pointless to test here */
+    if (streams.length) {
+      this.push(...streams)
+    }
+  }
+
+  on (event, handler) {
+    if (this.#events.includes(event) && this.#data.has(event)) {
+      return handler(...this.#data.get(event))
+    }
+
+    return super.on(event, handler)
+  }
+
+  emit (event, ...data) {
+    if (this.#events.includes(event)) {
+      this.#data.set(event, data)
+    }
+
+    return super.emit(event, ...data)
+  }
+}
+
+module.exports = CachingMinipassPipeline