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/websocket-extensions/lib/pipeline/index.js

@@ -0,0 +1,47 @@
+'use strict';
+
+var Cell   = require('./cell'),
+    Pledge = require('./pledge');
+
+var Pipeline = function(sessions) {
+  this._cells   = sessions.map(function(session) { return new Cell(session) });
+  this._stopped = { incoming: false, outgoing: false };
+};
+
+Pipeline.prototype.processIncomingMessage = function(message, callback, context) {
+  if (this._stopped.incoming) return;
+  this._loop('incoming', this._cells.length - 1, -1, -1, message, callback, context);
+};
+
+Pipeline.prototype.processOutgoingMessage = function(message, callback, context) {
+  if (this._stopped.outgoing) return;
+  this._loop('outgoing', 0, this._cells.length, 1, message, callback, context);
+};
+
+Pipeline.prototype.close = function(callback, context) {
+  this._stopped = { incoming: true, outgoing: true };
+
+  var closed = this._cells.map(function(a) { return a.close() });
+  if (callback)
+    Pledge.all(closed).then(function() { callback.call(context) });
+};
+
+Pipeline.prototype._loop = function(direction, start, end, step, message, callback, context) {
+  var cells = this._cells,
+      n     = cells.length,
+      self  = this;
+
+  while (n--) cells[n].pending(direction);
+
+  var pipe = function(index, error, msg) {
+    if (index === end) return callback.call(context, error, msg);
+
+    cells[index][direction](error, msg, function(err, m) {
+      if (err) self._stopped[direction] = true;
+      pipe(index + step, err, m);
+    });
+  };
+  pipe(start, null, message);
+};
+
+module.exports = Pipeline;