feat: Features架构迁移 - P0和P1部分完成

## 完成的工作

### P0: 基础设施准备
- 创建 features/ 和 shared/ 目录结构
- 迁移共享资源：API基础设施、工具函数、类型定义
- 迁移通用composables：useMoney, useSmsCountdown, usePricingCalculator
- 迁移全局样式文件
- 建立模块化导出系统

### P1.1: 钱包模块 (wallet)
- 迁移 API: wallet.ts
- 迁移 Views: WalletView.vue
- 新增 Composable: useWallet.ts (封装钱包状态管理)
- 更新导入路径到 shared/

### P1.2: 聊天模块 (chats)
- 迁移 API: chats.ts
- 迁移 Views: ChatView, MessagesView (桌面+移动)
- 迁移 Composables: useChatSSE.ts
- 迁移 Components: ChatAttachmentImage.vue
- 更新导入路径到 shared/

## 技术改进
- 修复 shared/composables 导出问题 (default → 命名导出)
- 修复 shared/api/client.ts 类型导入路径
- 建立清晰的模块边界和导出规范

## 文档
- 添加完整的迁移计划文档
- 添加进度跟踪文档

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/features/wallet/api/wallet.ts

@@ -0,0 +1,54 @@
+import { apiClient } from '@/shared/api/client'
+
+import type { ApiResponse, PaginatedResult } from '@/shared/types/types'
+import type { BalanceType, LedgerDirection, WalletStatus } from '@/shared/types/status'
+import type { PaymentOrder } from '@/api/orders'
+
+export interface WalletAccount {
+  user_id: number
+  available_balance: number
+  frozen_balance: number
+  status: WalletStatus
+}
+
+export interface WalletLedger {
+  id: number
+  ledger_no: string
+  user_id: number
+  order_id?: number
+  direction: LedgerDirection
+  amount: number
+  balance_after: number
+  balance_type: BalanceType
+  biz_type: string
+  biz_no: string
+  remark: string
+  created_at: string
+}
+
+export async function fetchWalletBalance() {
+  const { data } = await apiClient.get<ApiResponse<WalletAccount>>('/wallet/balance')
+  return data.data
+}
+
+export async function fetchWalletLedger(page = 1, pageSize = 20) {
+  const { data } = await apiClient.get<ApiResponse<PaginatedResult<WalletLedger>>>('/wallet/ledger', {
+    params: { page, page_size: pageSize },
+  })
+  return data.data
+}
+
+export async function rechargeWallet(amount: number) {
+  const { data } = await apiClient.post<ApiResponse<WalletAccount>>('/wallet/recharge', { amount })
+  return data.data
+}
+
+export async function startWalletRechargePayment(amount: number) {
+  const { data } = await apiClient.post<ApiResponse<PaymentOrder>>('/wallet/recharge/pay', { amount })
+  return data.data
+}
+
+export async function queryWalletRechargePayment(id: number) {
+  const { data } = await apiClient.post<ApiResponse<PaymentOrder>>(`/wallet/recharge/pay/${id}/query`)
+  return data.data
+}