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/flex-flow.js

@@ -0,0 +1,53 @@
+let flexSpec = require('./flex-spec')
+let Declaration = require('../declaration')
+
+class FlexFlow extends Declaration {
+  /**
+   * Use two properties for 2009 spec
+   */
+  insert(decl, prefix, prefixes) {
+    let spec
+    ;[spec, prefix] = flexSpec(prefix)
+    if (spec !== 2009) {
+      return super.insert(decl, prefix, prefixes)
+    }
+    let values = decl.value
+      .split(/\s+/)
+      .filter(i => i !== 'wrap' && i !== 'nowrap' && 'wrap-reverse')
+    if (values.length === 0) {
+      return undefined
+    }
+
+    let already = decl.parent.some(
+      i =>
+        i.prop === prefix + 'box-orient' || i.prop === prefix + 'box-direction'
+    )
+    if (already) {
+      return undefined
+    }
+
+    let value = values[0]
+    let orient = value.includes('row') ? 'horizontal' : 'vertical'
+    let dir = value.includes('reverse') ? 'reverse' : 'normal'
+
+    let cloned = this.clone(decl)
+    cloned.prop = prefix + 'box-orient'
+    cloned.value = orient
+    if (this.needCascade(decl)) {
+      cloned.raws.before = this.calcBefore(prefixes, decl, prefix)
+    }
+    decl.parent.insertBefore(decl, cloned)
+
+    cloned = this.clone(decl)
+    cloned.prop = prefix + 'box-direction'
+    cloned.value = dir
+    if (this.needCascade(decl)) {
+      cloned.raws.before = this.calcBefore(prefixes, decl, prefix)
+    }
+    return decl.parent.insertBefore(decl, cloned)
+  }
+}
+
+FlexFlow.names = ['flex-flow', 'box-direction', 'box-orient']
+
+module.exports = FlexFlow