fix: keep project dialog close controls clickable

Render project creation and settings dialogs in a body portal so the Electron title-bar drag region does not intercept their close controls. Cover dialog placement, scrolling, and focus restoration, and document the layout rule.

Release note: Project creation and settings dialogs keep their close buttons clickable after scrolling and restore focus to their trigger when closed.

UI-DESIGN.md

@@ -709,6 +709,7 @@ GoodBuddy 是可调整窗口大小的桌面应用。响应式设计优先保证
 
 - 全页设置使用固定标题区、左侧分类导航和独立滚动的内容区。右上角关闭按钮是离开设置中心的稳定入口。
 - 新建项目与项目设置弹窗固定标题、关闭按钮和底部操作区，仅表单内容滚动；滚动条不进入标题区，关闭按钮保留至少 40 × 40px 的点击区域。
+- 项目弹窗通过 Portal 挂载到 `document.body`，避免侧栏内的弹窗与主窗口标题栏拖动区域重叠时，Electron 截获关闭按钮的鼠标输入。
 - 左侧分类导航在宽屏使用 `220px`，中等窗口使用 `196px`，窄窗口转为横向滚动；纵向滚动条仅在内容溢出时占用右侧空间，不在左侧创建镜像预留，选项与左侧可见边界保持默认内距。分类标题使用正文级字号，分类说明使用辅助字号；右侧内容区在可用空间内流式伸缩，最大宽度使用 `standard` 壳层的 `960px`，不得以页面专属较窄宽度压缩表单。
 - 全页设置标题区与双栏内容使用共享 `--page-gutter`，标题、分类导航和内容区在同一页面边距基线上；标题继续使用标准 `PageHeader` 的底部分隔线与下内距。固定标题和双独立滚动区域不改变这些一级页面壳层规则；模态设置保留自身外框与标题边界。
 - 设置中心不显示全局操作页脚，避免重复关闭入口和没有功能意义的整宽分隔线。

src/renderer/src/ProjectSwitcher.test.tsx

@@ -354,6 +354,23 @@ describe('ProjectSwitcher project activity integration', () => {
 })
 
 describe('ProjectSwitcher runtime fields', () => {
+  it.each(['新建项目', '项目设置'])('keeps %s outside the sidebar and restores focus after closing', (name) => {
+    renderSwitcher()
+    const trigger = screen.getByLabelText(name)
+    fireEvent.click(trigger)
+    const dialog = screen.getByRole('dialog', { name })
+    expect(dialog.parentElement?.parentElement).toBe(document.body)
+    const body = dialog.querySelector('.project-create-card__body')!
+    const close = within(dialog).getByRole('button', { name: `关闭${name}` })
+    expect(body).toContainElement(within(dialog).getByLabelText('名称'))
+    expect(body).not.toContainElement(close)
+    expect(body).not.toContainElement(within(dialog).getByRole('button', { name: '取消' }))
+    fireEvent.scroll(body, { target: { scrollTop: 500 } })
+    fireEvent.click(close)
+    expect(screen.queryByRole('dialog', { name })).not.toBeInTheDocument()
+    expect(trigger).toHaveFocus()
+  })
+
   it('creates an ordinary project with DeepSeek Harness', async () => {
     const { onCreate } = renderSwitcher()
 

src/renderer/src/ProjectSwitcher.tsx

@@ -17,6 +17,7 @@ import {
 } from 'lucide-react'
 import type { LucideIcon } from 'lucide-react'
 import { useCallback, useEffect, useRef, useState } from 'react'
+import { createPortal } from 'react-dom'
 import { useTranslation } from 'react-i18next'
 import type {
   AssistantProject,
@@ -1413,7 +1414,7 @@ export function ProjectSwitcher({
           <Settings size={15} />
         </button>
       </div>
-      {dialogMode && (
+      {dialogMode && createPortal(
         <div
           className="project-create-backdrop"
           onMouseDown={(event) => {
@@ -2139,7 +2140,8 @@ export function ProjectSwitcher({
               )}
             </div>
           </div>
-        </div>
+        </div>,
+        document.body
       )}
     </div>
   )