feat(rectifier): 请求整流器增加 API Key 账号签名整流支持

新增独立开关控制 API Key 账号的签名整流功能，支持配置自定义
匹配关键词以捕获不同格式的上游错误响应。

- 新增 apikey_signature_enabled 开关（默认关闭）
- 新增 apikey_signature_patterns 自定义关键词配置
- 内置签名检测规则对 API Key 账号同样生效
- 自定义关键词对完整响应体做不区分大小写匹配
- 重试二阶段检测仅做模式匹配，不重复校验开关
- Handler 层校验关键词数量（≤50）和长度（≤500）
- API 响应 nil patterns 统一序列化为空数组
- OAuth/SetupToken/Upstream/Bedrock 账号行为不变

frontend/src/i18n/locales/en.ts

@@ -4473,6 +4473,14 @@ export default {
         thinkingSignatureHint: 'Automatically strip signatures and retry when upstream returns thinking block signature validation errors',
         thinkingBudget: 'Thinking Budget Rectifier',
         thinkingBudgetHint: 'Automatically set budget to 32000 and retry when upstream returns budget_tokens constraint error (≥1024)',
+        apikeySignature: 'API Key Signature Rectifier',
+        apikeySignatureHint:
+          'Automatically strip signatures and retry when API Key accounts receive signature-related errors (built-in patterns always apply)',
+        apikeyPatterns: 'Custom Match Patterns',
+        apikeyPatternsHint:
+          'Additional keywords matched against the response body (case-insensitive). Built-in patterns always apply; use these for supplementary matching.',
+        apikeyPatternPlaceholder: 'e.g., thinking_error',
+        addPattern: 'Add Pattern',
         saved: 'Rectifier settings saved',
         saveFailed: 'Failed to save rectifier settings'
       },

frontend/src/i18n/locales/zh.ts

@@ -4637,6 +4637,14 @@ export default {
         thinkingSignatureHint: '当上游返回 thinking block 签名校验错误时，自动去除签名并重试',
         thinkingBudget: 'Thinking Budget 整流',
         thinkingBudgetHint: '当上游返回 budget_tokens 约束错误（≥1024）时，自动将 budget 设为 32000 并重试',
+        apikeySignature: 'API Key 签名整流',
+        apikeySignatureHint:
+          '当 API Key 账号的上游返回签名相关错误时，自动去除签名并重试（内置规则始终生效）',
+        apikeyPatterns: '自定义匹配关键词',
+        apikeyPatternsHint:
+          '额外的关键词，匹配响应体中的内容（不区分大小写）。内置规则始终生效，此处用于补充额外匹配。',
+        apikeyPatternPlaceholder: '例如：thinking_error 或 签名无效',
+        addPattern: '添加关键词',
         saved: '整流器设置保存成功',
         saveFailed: '保存整流器设置失败'
       },