fix(canvas): 模型选择 - 画布拖拽前关闭悬浮菜单

Fixes #138

web/src/components/model-picker.tsx

@@ -62,6 +62,19 @@ export function ModelPicker({ config, value, onChange, capability, className, fu
         return () => window.removeEventListener("model-picker-open", closeOtherPicker);
     }, [pickerId]);
 
+    useEffect(() => {
+        if (!open) return;
+        // 画布拖拽从 pointerdown 开始，须在捕获阶段关闭 Portal 菜单，避免菜单与触发器分离。
+        const closeOnOutsidePointer = (event: PointerEvent) => {
+            const target = event.target;
+            if (!(target instanceof Node)) return;
+            if (triggerRef.current?.contains(target) || menuRef.current?.contains(target)) return;
+            setOpen(false);
+        };
+        window.addEventListener("pointerdown", closeOnOutsidePointer, true);
+        return () => window.removeEventListener("pointerdown", closeOnOutsidePointer, true);
+    }, [open]);
+
     const setPickerOpen = (nextOpen: boolean) => {
         if (nextOpen && !options.length && config.channelMode === "local") onMissingConfig?.();
         if (nextOpen) window.dispatchEvent(new CustomEvent("model-picker-open", { detail: pickerId }));