feat: add AI Credits balance handling and update model status indicators

frontend/src/i18n/locales/en.ts

@@ -1867,6 +1867,7 @@ export default {
         rateLimitedUntil: 'Rate limited and removed from scheduling. Auto resumes at {time}',
         rateLimitedAutoResume: 'Auto resumes in {time}',
         modelRateLimitedUntil: '{model} rate limited until {time}',
+        modelCreditOveragesUntil: '{model} using AI Credits until {time}',
         overloadedUntil: 'Overloaded until {time}',
         viewTempUnschedDetails: 'View temp unschedulable details'
       },
@@ -2239,6 +2240,7 @@ export default {
       mixedSchedulingHint: 'Enable to participate in Anthropic/Gemini group scheduling',
       mixedSchedulingTooltip:
         '!! WARNING !! Antigravity Claude and Anthropic Claude cannot be used in the same context. If you have both Anthropic and Antigravity accounts, enabling this option will cause frequent 400 errors. When enabled, please use the group feature to isolate Antigravity accounts from Anthropic accounts. Make sure you understand this before enabling!!',
+      aiCreditsBalance: 'AI Credits',
       allowOverages: 'Allow Overages (AI Credits)',
       allowOveragesTooltip:
         'Only use AI Credits after free quota is explicitly exhausted. Ordinary concurrent 429 rate limits will not switch to overages.',

frontend/src/i18n/locales/zh.ts

@@ -2052,6 +2052,7 @@ export default {
         rateLimitedUntil: '限流中，当前不参与调度，预计 {time} 自动恢复',
         rateLimitedAutoResume: '{time} 自动恢复',
         modelRateLimitedUntil: '{model} 限流至 {time}',
+        modelCreditOveragesUntil: '{model} 正在使用 AI Credits，至 {time}',
         overloadedUntil: '负载过重，重置时间：{time}',
         viewTempUnschedDetails: '查看临时不可调度详情'
       },
@@ -2389,6 +2390,7 @@ export default {
       mixedSchedulingHint: '启用后可参与 Anthropic/Gemini 分组的调度',
       mixedSchedulingTooltip:
         '！！注意！！ Antigravity Claude 和 Anthropic Claude 无法在同个上下文中使用，如果你同时有 Anthropic 账号和 Antigravity 账号，开启此选项会导致经常 400 报错。开启后，请用分组功能做好 Antigravity 账号和 Anthropic 账号的隔离。一定要弄明白再开启！！',
+      aiCreditsBalance: 'AI Credits',
       allowOverages: '允许超量请求 (AI Credits)',
       allowOveragesTooltip:
         '仅在免费配额被明确判定为耗尽后才会使用 AI Credits。普通并发 429 限流不会切换到超量请求。',