feat: add Cache TTL Override per account + bump VERSION to 0.1.83

- Account-level cache TTL override: rewrite Anthropic cache_creation
  token classification (5m↔1h) in streaming/non-streaming responses
- New DB field cache_ttl_overridden in usage_log for billing tracking
- Migration 055_add_cache_ttl_overridden
- Frontend: CacheTTL override toggle in account create/edit modals
- Ent schema regenerated for new usage_log fields

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/internal/handler/dto/mappers.go

@@ -211,6 +211,13 @@ func AccountFromServiceShallow(a *service.Account) *Account {
 			enabled := true
 			out.EnableSessionIDMasking = &enabled
 		}
+		// 缓存 TTL 强制替换
+		if a.IsCacheTTLOverrideEnabled() {
+			enabled := true
+			out.CacheTTLOverrideEnabled = &enabled
+			target := a.GetCacheTTLOverrideTarget()
+			out.CacheTTLOverrideTarget = &target
+		}
 	}
 
 	return out
@@ -398,6 +405,7 @@ func usageLogFromServiceUser(l *service.UsageLog) UsageLog {
 		ImageCount:            l.ImageCount,
 		ImageSize:             l.ImageSize,
 		UserAgent:             l.UserAgent,
+		CacheTTLOverridden:    l.CacheTTLOverridden,
 		CreatedAt:             l.CreatedAt,
 		User:                  UserFromServiceShallow(l.User),
 		APIKey:                APIKeyFromService(l.APIKey),

backend/internal/handler/dto/types.go

@@ -150,6 +150,11 @@ type Account struct {
 	// 从 extra 字段提取，方便前端显示和编辑
 	EnableSessionIDMasking *bool `json:"session_id_masking_enabled,omitempty"`
 
+	// 缓存 TTL 强制替换（仅 Anthropic OAuth/SetupToken 账号有效）
+	// 启用后将所有 cache creation tokens 归入指定的 TTL 类型计费
+	CacheTTLOverrideEnabled *bool   `json:"cache_ttl_override_enabled,omitempty"`
+	CacheTTLOverrideTarget  *string `json:"cache_ttl_override_target,omitempty"`
+
 	Proxy         *Proxy         `json:"proxy,omitempty"`
 	AccountGroups []AccountGroup `json:"account_groups,omitempty"`
 
@@ -273,6 +278,9 @@ type UsageLog struct {
 	// User-Agent
 	UserAgent *string `json:"user_agent"`
 
+	// Cache TTL Override 标记
+	CacheTTLOverridden bool `json:"cache_ttl_overridden"`
+
 	CreatedAt time.Time `json:"created_at"`
 
 	User         *User             `json:"user,omitempty"`