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/tab/index.css

@@ -4,44 +4,46 @@
     width: 100%;
     height: 100%;
     background: transparent;
-    color: var(--bim-tab-text, #e6e6e6);
+    color: var(--bim-text-secondary);
 }
 
 .bim-tab__nav {
     display: flex;
     align-items: center;
-    justify-content: space-around;
-    background: transparent;
+    gap: 4px;
+    padding: 4px;
+    margin: 8px 12px;
+    background: var(--bim-bg-inset);
+    border-radius: 8px;
+    border: 1px solid var(--bim-border-subtle);
 }
 
 .bim-tab__item {
-    flex:1;
+    flex: 1;
     display: inline-flex;
     align-items: center;
     justify-content: center;
     gap: 6px;
-    /* 恢复原样式：上下4px，左右0 */
-    padding: 4px 0;
+    padding: 8px 12px;
     border: none;
-    border-radius: 0; /* 恢复直角 */
+    border-radius: 6px;
     background: transparent;
-    color: var(--bim-tab-text, #e6e6e6);
+    color: var(--bim-text-secondary);
     cursor: pointer;
     transition: all 0.2s ease;
-    font-size: 14px;
-    border-bottom: 4px solid transparent;
+    font-size: 13px;
+    font-weight: 500;
 }
 
 .bim-tab__item:hover {
-    color: var(--bim-tab-text, #e6e6e6);
-    background-color: var(--bim-tab-hover-bg, rgba(255, 255, 255, 0.05));
-    border-bottom-color: var(--bim-tab-hover-bg, rgba(255, 255, 255, 0.15));
+    color: var(--bim-text-primary);
+    background-color: var(--bim-component-bg-hover);
 }
 
-/* Active 状态 */
 .bim-tab__item.is-active {
-    color: var(--bim-tab-text-active, #4da3ff);
-    border-bottom-color: var(--bim-tab-text-active, #4da3ff);
+    color: var(--bim-primary);
+    background-color: var(--bim-bg-elevated);
+    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
 }
 
 .bim-tab__item.is-disabled {