refactor: 重命名SDK为iflow-engine，使用npm包引入第三方引擎

- 将包名从 @fishdingding/bim-engine-sdk 改为 iflow-engine
- 将构建输出文件从 bim-engine-sdk.*.js 改为 iflow-engine.*.js
- 将全局变量从 LyzBimEngineSDK 改为 IflowEngine
- 将第三方引擎SDK从本地引入改为npm包引入 (iflow-engine-base)
- 移除本地 src/engine_base 目录，移至回收站
- 更新所有文档和demo中的引用

src/components/menu/index.css

@@ -2,8 +2,9 @@
     display: flex;
     flex-direction: column;
     background: var(--bim-bg-elevated);
-    border-radius: 4px;
-    padding: 4px 0;
+    border: 1px solid var(--bim-border-default);
+    border-radius: 8px;
+    padding: 6px;
     margin: 0;
     list-style: none;
     min-width: 160px;
@@ -27,16 +28,18 @@
 .bim-menu-item {
     display: flex;
     align-items: center;
-    padding: 6px 12px;
+    padding: 8px 12px;
     cursor: pointer;
-    transition: background-color 0.2s;
+    transition: all 0.2s ease;
     font-size: 13px;
     position: relative;
     color: var(--bim-text-primary);
+    border-radius: 6px;
 }
 
 .bim-menu-item:hover {
-    background-color: var(--bim-component-bg-hover);
+    background-color: var(--bim-floating-btn-bg);
+    transform: translateX(2px);
 }
 
 .bim-menu-item.disabled {