feat: 算力引擎 Go 后端核心（new-api）

- 统一 OpenAI 兼容 /v1 中继 + 渠道/额度/令牌/流水
- 各领域包：relay 模型网关、model 数据层、controller 管理 API

service/openai_chat_responses_mode.go

@@ -0,0 +1,54 @@
+package service
+
+import (
+	"regexp"
+	"sync"
+
+	"github.com/QuantumNous/new-api/setting/model_setting"
+)
+
+// Chat→Responses upgrade policy is host routing logic (it decides *whether*
+// to convert, reading host settings), so it lives here, not in relayconvert.
+
+var chatResponsesRegexCache sync.Map // map[string]*regexp.Regexp
+
+func matchAnyModelPattern(patterns []string, model string) bool {
+	if len(patterns) == 0 || model == "" {
+		return false
+	}
+	for _, pattern := range patterns {
+		if pattern == "" {
+			continue
+		}
+		re, ok := chatResponsesRegexCache.Load(pattern)
+		if !ok {
+			compiled, err := regexp.Compile(pattern)
+			if err != nil {
+				// Treat invalid patterns as non-matching to avoid breaking runtime traffic.
+				continue
+			}
+			re = compiled
+			chatResponsesRegexCache.Store(pattern, re)
+		}
+		if re.(*regexp.Regexp).MatchString(model) {
+			return true
+		}
+	}
+	return false
+}
+
+func ShouldChatCompletionsUseResponsesPolicy(policy model_setting.ChatCompletionsToResponsesPolicy, channelID int, channelType int, model string) bool {
+	if !policy.IsChannelEnabled(channelID, channelType) {
+		return false
+	}
+	return matchAnyModelPattern(policy.ModelPatterns, model)
+}
+
+func ShouldChatCompletionsUseResponsesGlobal(channelID int, channelType int, model string) bool {
+	return ShouldChatCompletionsUseResponsesPolicy(
+		model_setting.GetGlobalSettings().ChatCompletionsToResponsesPolicy,
+		channelID,
+		channelType,
+		model,
+	)
+}