feat(mindspace): 悬浮聊天勾选资料联动、UI 与交互优化

勾选单个文件时 Agent 获知上下文并主动问候；打开悬浮窗使用新会话。
统一弹窗浅色主题、固定高度与输入区布局，支持点击外部收起。

Co-authored-by: Cursor <cursoragent@cursor.com>

src/components/MindSpaceView.tsx

@@ -667,6 +667,14 @@ export function MindSpaceView({
     return () => document.removeEventListener('pointerdown', handlePointerDown);
   }, [openAssetMenuId]);
 
+  const selectedAssetsForChat = useMemo(
+    () =>
+      selectedAssetIds
+        .map((id) => assets.find((asset) => asset.id === id))
+        .filter((asset): asset is MindSpaceAsset => Boolean(asset)),
+    [selectedAssetIds, assets],
+  );
+
   const mindspaceChatContext = useMemo(() => {
     if (!space) return null;
     return buildMindSpaceChatContext({
@@ -677,7 +685,7 @@ export function MindSpaceView({
       pages,
       pageLive: pageLiveContext,
       assets,
-      focusedAsset: agentAsset,
+      selectedAssets: selectedAssetsForChat,
       route: `${location.pathname}${location.search}`,
       agentSessionId: session?.id ?? null,
       h5ApiBase,
@@ -690,7 +698,7 @@ export function MindSpaceView({
     pages,
     pageLiveContext,
     assets,
-    agentAsset,
+    selectedAssetsForChat,
     location.pathname,
     location.search,
     session?.id,