feat(admin): 新增账户余额/配额查询与展示

- 新增 accountBalanceService 与多 Provider 适配（Claude/Claude Console/OpenAI Responses/通用）
  - Redis 增加余额查询结果与本地统计缓存读写
  - 管理端新增 /admin/accounts/balance 相关接口与汇总接口，并在应用启动时注册 Provider
  - 后台前端新增余额组件与 Dashboard 余额/配额汇总、低余额/高使用提示
  - 补充 accountBalanceService 单元测试

tests/accountBalanceService.test.js

@@ -0,0 +1,142 @@
+// Mock logger，避免测试输出污染控制台
+jest.mock('../src/utils/logger', () => ({
+  debug: jest.fn(),
+  info: jest.fn(),
+  warn: jest.fn(),
+  error: jest.fn()
+}))
+
+const accountBalanceServiceModule = require('../src/services/accountBalanceService')
+
+const { AccountBalanceService } = accountBalanceServiceModule
+
+describe('AccountBalanceService', () => {
+  const mockLogger = {
+    debug: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: jest.fn()
+  }
+
+  const buildMockRedis = () => ({
+    getLocalBalance: jest.fn().mockResolvedValue(null),
+    setLocalBalance: jest.fn().mockResolvedValue(undefined),
+    getAccountBalance: jest.fn().mockResolvedValue(null),
+    setAccountBalance: jest.fn().mockResolvedValue(undefined),
+    deleteAccountBalance: jest.fn().mockResolvedValue(undefined),
+    getAccountUsageStats: jest.fn().mockResolvedValue({
+      total: { requests: 10 },
+      daily: { requests: 2, cost: 20 },
+      monthly: { requests: 5 }
+    }),
+    getDateInTimezone: (date) => new Date(date.getTime() + 8 * 3600 * 1000)
+  })
+
+  it('should normalize platform aliases', () => {
+    const service = new AccountBalanceService({ redis: buildMockRedis(), logger: mockLogger })
+    expect(service.normalizePlatform('claude-official')).toBe('claude')
+    expect(service.normalizePlatform('azure-openai')).toBe('azure_openai')
+    expect(service.normalizePlatform('gemini-api')).toBe('gemini-api')
+  })
+
+  it('should build local quota/balance from dailyQuota and local dailyCost', async () => {
+    const mockRedis = buildMockRedis()
+    const service = new AccountBalanceService({ redis: mockRedis, logger: mockLogger })
+
+    service._computeMonthlyCost = jest.fn().mockResolvedValue(30)
+    service._computeTotalCost = jest.fn().mockResolvedValue(123.45)
+
+    const account = { id: 'acct-1', name: 'A', dailyQuota: '100', quotaResetTime: '00:00' }
+    const result = await service._getAccountBalanceForAccount(account, 'claude-console', {
+      queryApi: false,
+      useCache: true
+    })
+
+    expect(result.success).toBe(true)
+    expect(result.data.source).toBe('local')
+    expect(result.data.balance.amount).toBeCloseTo(80, 6)
+    expect(result.data.quota.percentage).toBeCloseTo(20, 6)
+    expect(result.data.statistics.totalCost).toBeCloseTo(123.45, 6)
+    expect(mockRedis.setLocalBalance).toHaveBeenCalled()
+  })
+
+  it('should use cached balance when account has no dailyQuota', async () => {
+    const mockRedis = buildMockRedis()
+    mockRedis.getAccountBalance.mockResolvedValue({
+      status: 'success',
+      balance: 12.34,
+      currency: 'USD',
+      quota: null,
+      errorMessage: '',
+      lastRefreshAt: '2025-01-01T00:00:00Z',
+      ttlSeconds: 120
+    })
+
+    const service = new AccountBalanceService({ redis: mockRedis, logger: mockLogger })
+    service._computeMonthlyCost = jest.fn().mockResolvedValue(0)
+    service._computeTotalCost = jest.fn().mockResolvedValue(0)
+
+    const account = { id: 'acct-2', name: 'B' }
+    const result = await service._getAccountBalanceForAccount(account, 'openai', {
+      queryApi: false,
+      useCache: true
+    })
+
+    expect(result.data.source).toBe('cache')
+    expect(result.data.balance.amount).toBeCloseTo(12.34, 6)
+    expect(result.data.lastRefreshAt).toBe('2025-01-01T00:00:00Z')
+  })
+
+  it('should cache provider errors and fallback to local when queryApi=true', async () => {
+    const mockRedis = buildMockRedis()
+    const service = new AccountBalanceService({ redis: mockRedis, logger: mockLogger })
+
+    service._computeMonthlyCost = jest.fn().mockResolvedValue(0)
+    service._computeTotalCost = jest.fn().mockResolvedValue(0)
+
+    service.registerProvider('openai', {
+      queryBalance: () => {
+        throw new Error('boom')
+      }
+    })
+
+    const account = { id: 'acct-3', name: 'C' }
+    const result = await service._getAccountBalanceForAccount(account, 'openai', {
+      queryApi: true,
+      useCache: false
+    })
+
+    expect(mockRedis.setAccountBalance).toHaveBeenCalled()
+    expect(result.data.source).toBe('local')
+    expect(result.data.status).toBe('error')
+    expect(result.data.error).toBe('boom')
+  })
+
+  it('should count low balance once per account in summary', async () => {
+    const mockRedis = buildMockRedis()
+    const service = new AccountBalanceService({ redis: mockRedis, logger: mockLogger })
+
+    service.getSupportedPlatforms = () => ['claude-console']
+    service.getAllAccountsByPlatform = async () => [{ id: 'acct-4', name: 'D' }]
+    service._getAccountBalanceForAccount = async () => ({
+      success: true,
+      data: {
+        accountId: 'acct-4',
+        platform: 'claude-console',
+        balance: { amount: 5, currency: 'USD', formattedAmount: '$5.00' },
+        quota: { percentage: 95 },
+        statistics: { totalCost: 1 },
+        source: 'local',
+        lastRefreshAt: '2025-01-01T00:00:00Z',
+        cacheExpiresAt: null,
+        status: 'success',
+        error: null
+      }
+    })
+
+    const summary = await service.getBalanceSummary()
+    expect(summary.lowBalanceCount).toBe(1)
+    expect(summary.platforms['claude-console'].lowBalanceCount).toBe(1)
+  })
+})
+