feat(codex): add credits balance to quota query

- Parse Codex usage credits balance and unlimited status
- Display credits in quota cards and auth file panels
- Add i18n labels and related tests

tests/quotaRequests.test.ts

@@ -5,6 +5,7 @@ import { consumeCodexResetCredit, loadQuota } from '../src/services/quotaService
 const success = (body: unknown) => ({ status_code: 200, body });
 const codexUsage = {
   rate_limit: { primary_window: { used_percent: 25, limit_window_seconds: 18000 } },
+  credits: { balance: 12.5, unlimited: false },
   rate_limit_reset_credits: { available_count: 2, applicable_available_count: 0 },
 };
 const codexFile = { name: 'codex-test.json', provider: 'codex', auth_index: 1 };
@@ -39,7 +40,7 @@ describe('quota API compatibility', () => {
       ...codexFile,
       metadata: { id_token: { chatgpt_account_id: 'account-test', plan_type: 'pro', chatgpt_subscription_active_until: '2030-01-01T00:00:00Z' } },
     });
-    expect(result).toMatchObject({ status: 'success', plan: 'pro', resetCredits: 2, resetCreditsApplicable: 0, resetCreditsError: 'credits forbidden' });
+    expect(result).toMatchObject({ status: 'success', plan: 'pro', creditBalance: '12.5', creditsUnlimited: false, resetCredits: 2, resetCreditsApplicable: 0, resetCreditsError: 'credits forbidden' });
     expect(result.subscriptionActiveUntil).toBe('2030-01-01T00:00:00Z');
     expect(calls).toHaveLength(2);
     for (const call of calls) {

tests/quotaService.test.ts

@@ -1,10 +1,25 @@
 import { describe, expect, it } from 'bun:test';
 import {
+  codexAccountCreditsFor,
   codexResetCreditDetailsFor,
   codexResetCreditsFor,
   quotaRowsFor,
 } from '../src/services/quotaService';
 
+describe('Codex account credits', () => {
+  it('reads a numeric balance and unlimited flag from usage payloads', () => {
+    expect(codexAccountCreditsFor({ credits: { balance: 12.5, unlimited: false } }))
+      .toEqual({ balance: '12.5', unlimited: false });
+    expect(codexAccountCreditsFor({ credits: { unlimited: true } }))
+      .toEqual({ unlimited: true });
+  });
+
+  it('ignores malformed balances', () => {
+    expect(codexAccountCreditsFor({ credits: { balance: 'N/A', unlimited: false } }))
+      .toEqual({ unlimited: false });
+  });
+});
+
 describe('quotaRowsFor', () => {
   it('把 Codex 的已用百分比转换为剩余额度', () => {
     const rows = quotaRowsFor('codex', {