📦 添加虚拟环境和启动脚本

新增:
- backend/venv/ - Python 虚拟环境
- backend/start.sh - 启动脚本（使用虚拟环境）
- backend/requirements.txt - 依赖列表
- .gitignore - 忽略虚拟环境和缓存文件

说明:
- 每个项目使用独立虚拟环境
- 避免依赖冲突
- 启动脚本自动创建和激活虚拟环境

frontend/node_modules/faye-websocket/lib/faye/websocket/api/event.js

@@ -0,0 +1,22 @@
+'use strict';
+
+var Event = function(eventType, options) {
+  this.type = eventType;
+  for (var key in options)
+    this[key] = options[key];
+};
+
+Event.prototype.initEvent = function(eventType, canBubble, cancelable) {
+  this.type       = eventType;
+  this.bubbles    = canBubble;
+  this.cancelable = cancelable;
+};
+
+Event.prototype.stopPropagation = function() {};
+Event.prototype.preventDefault  = function() {};
+
+Event.CAPTURING_PHASE = 1;
+Event.AT_TARGET       = 2;
+Event.BUBBLING_PHASE  = 3;
+
+module.exports = Event;

frontend/node_modules/faye-websocket/lib/faye/websocket/api/event_target.js

@@ -0,0 +1,30 @@
+'use strict';
+
+var Event = require('./event');
+
+var EventTarget = {
+  onopen:     null,
+  onmessage:  null,
+  onerror:    null,
+  onclose:    null,
+
+  addEventListener: function(eventType, listener, useCapture) {
+    this.on(eventType, listener);
+  },
+
+  removeEventListener: function(eventType, listener, useCapture) {
+    this.removeListener(eventType, listener);
+  },
+
+  dispatchEvent: function(event) {
+    event.target = event.currentTarget = this;
+    event.eventPhase = Event.AT_TARGET;
+
+    if (this['on' + event.type])
+      this['on' + event.type](event);
+
+    this.emit(event.type, event);
+  }
+};
+
+module.exports = EventTarget;