refactor: Context 与 Provider 合并 — 消除 contexts/ 目录，一文件一状态单元

- ThemeContext + useTheme → ThemeProvider.tsx（原 hooks/use-theme.ts 删除）
- AppContext + useAppContext → AppProvider.tsx（原 contexts/app-context.ts 删除）
- SettingsContext + useSettings → SettingsProvider.tsx（原 contexts/settings-context.ts 删除）
- HomeContext + useHomeContext → HomeContent.tsx（原 contexts/home-context.ts 删除）
- 删除空的 contexts/ 目录，20+ 导入路径同步更新
- TypeScript 编译通过（npx tsc --noEmit 零错误）

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/pages/settings/SettingsPage.tsx

@@ -14,7 +14,7 @@
 import { useCallback } from 'react';
 import { Modal } from 'antd';
 import { SettingOutlined, CloseOutlined } from '@ant-design/icons';
-import { useAppContext } from '@/contexts/app-context';
+import { useAppContext } from '@/components/AppProvider';
 import { isMacOS } from '@/utils/platform';
 import { ThemeSetting } from './blocks/ThemeSetting';
 import { StoragePathSetting } from './blocks/StoragePathSetting';

src/pages/settings/blocks/StoragePathSetting.tsx

@@ -9,7 +9,7 @@ import { useState, useCallback } from 'react';
 import { Card, Button, Input, Typography, Space, App } from 'antd';
 import { FolderOpenOutlined, DeleteOutlined, EditOutlined } from '@ant-design/icons';
 import type { Edition } from '@shared/types';
-import { useSettings } from '@/contexts/settings-context';
+import { useSettings } from '@/components/SettingsProvider';
 import { hasIpc, safeIpcInvoke } from '@/utils/ipc';
 import { BIDIRECTIONAL } from '@shared/constants/ipc-channels';
 

src/pages/settings/blocks/SystemInfoSetting.tsx

@@ -9,7 +9,7 @@ import {
    InfoCircleOutlined,
    EnvironmentOutlined,
 } from '@ant-design/icons';
-import { useAppContext } from '@/contexts/app-context';
+import { useAppContext } from '@/components/AppProvider';
 import { getPlatformName } from '@/utils/platform';
 import { APP_VERSION } from '@shared/constants/version';
 import { getEditionName } from '@shared/constants/app';

src/pages/settings/blocks/ThemeSetting.tsx

@@ -4,7 +4,7 @@
 
 import { Card, Segmented, Typography } from 'antd';
 import { BulbOutlined, BulbFilled } from '@ant-design/icons';
-import { useTheme } from '@/hooks/use-theme';
+import { useTheme } from '@/components/ThemeProvider';
 
 const { Text } = Typography;