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/autoprefixer/lib/hacks/grid-row-column.js

@@ -0,0 +1,33 @@
+let Declaration = require('../declaration')
+let utils = require('./grid-utils')
+
+class GridRowColumn extends Declaration {
+  /**
+   * Translate grid-row / grid-column to separate -ms- prefixed properties
+   */
+  insert(decl, prefix, prefixes) {
+    if (prefix !== '-ms-') return super.insert(decl, prefix, prefixes)
+
+    let values = utils.parse(decl)
+    let [start, span] = utils.translate(values, 0, 1)
+
+    let hasStartValueSpan = values[0] && values[0].includes('span')
+
+    if (hasStartValueSpan) {
+      span = values[0].join('').replace(/\D/g, '')
+    }
+
+    ;[
+      [decl.prop, start],
+      [`${decl.prop}-span`, span]
+    ].forEach(([prop, value]) => {
+      utils.insertDecl(decl, prop, value)
+    })
+
+    return undefined
+  }
+}
+
+GridRowColumn.names = ['grid-row', 'grid-column']
+
+module.exports = GridRowColumn