feat: implement resolveCreditsOveragesModelKey function to stabilize model key resolution for credit overages

frontend/src/i18n/locales/en.ts

@@ -2239,6 +2239,9 @@ 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!!',
+      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.',
       creating: 'Creating...',
       updating: 'Updating...',
       accountCreated: 'Account created successfully',

frontend/src/i18n/locales/zh.ts

@@ -2389,6 +2389,9 @@ 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！！',
+      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。',
       creating: '创建中...',
       updating: '更新中...',
       accountCreated: '账号创建成功',