feat: enhance text protocol conversion and advanced custom routing (#5825)

* refactor: consolidate relay protocol converters

* refactor relayconvert text converters

* feat: refine relay converters and advanced custom routing

* refactor: enhance logging and add thought signature handling for Gemini requests

* refactor: enhance channel cache and pricing endpoint handling for advanced custom models

* feat: preserve billing usage semantics

* feat: add protocol-aware billing usage

* Delete useless files

* chore: update action versions in workflow files

* chore: update Docker action versions in workflow files

* fix: harden billing usage settlement and hot-path route matching

- estimate Gemini completion tokens locally when billable usageMetadata is
  prompt-only but output content was received (e.g. client aborts the stream
  before the final chunk), and rebuild the attached billing_usage as estimated
  so settlement does not bill zero output tokens
- guard NewClaudeMessagesBillingUsage against all-zero ClaudeUsage, matching
  the OpenAI/Gemini constructors, so a zero billing_usage cannot override a
  non-zero top-level usage during settlement
- cache compiled advanced-custom route model regexes; they run on the request
  hot path and were recompiled per request
- move the effectiveBillingUsage remap to PostTextConsumeQuota only, and
  document that calculateTextQuotaSummary expects remapped usage
- document the updatePricingLock -> channelSyncLock lock ordering that
  InitChannelCache/CacheUpdateChannel rely on, and the aux-struct pitfall in
  GeminiChatResponse.UnmarshalJSON

relay/claude_handler.go

@@ -135,10 +135,14 @@ func ClaudeHelper(c *gin.Context, info *relaycommon.RelayInfo) (newAPIError *typ
 	if !model_setting.GetGlobalSettings().PassThroughRequestEnabled &&
 		!info.ChannelSetting.PassThroughBodyEnabled &&
 		service.ShouldChatCompletionsUseResponsesGlobal(info.ChannelId, info.ChannelType, info.OriginModelName) {
-		openAIRequest, convErr := service.ClaudeToOpenAIRequest(*request, info)
+		result, convErr := service.ConvertRequest(c, info, types.RelayFormatOpenAI, request)
 		if convErr != nil {
 			return types.NewError(convErr, types.ErrorCodeConvertRequestFailed, types.ErrOptionWithSkipRetry())
 		}
+		openAIRequest, ok := result.Value.(*dto.GeneralOpenAIRequest)
+		if !ok {
+			return types.NewError(fmt.Errorf("expected OpenAI chat completions request, got %T", result.Value), types.ErrorCodeConvertRequestFailed, types.ErrOptionWithSkipRetry())
+		}
 
 		usage, newApiErr := chatCompletionsViaResponses(c, info, adaptor, openAIRequest)
 		if newApiErr != nil {