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

relaykit/relayconvert/internal/shared/claude/cache.go

@@ -0,0 +1,9 @@
+package claude
+
+func NormalizeCacheCreationSplit(totalTokens int, tokens5m int, tokens1h int) (int, int) {
+	remainder := totalTokens - tokens5m - tokens1h
+	if remainder < 0 {
+		remainder = 0
+	}
+	return tokens5m + remainder, tokens1h
+}

relaykit/relayconvert/internal/shared/claude/errors.go

@@ -0,0 +1,10 @@
+package claude
+
+import "errors"
+
+// ErrMissingMaxTokens is returned when an OpenAI-format request carries no
+// usable max_tokens and no Options.Claude.DefaultMaxTokens hook is
+// configured. The Claude Messages API rejects requests without max_tokens
+// (400 "max_tokens: Field required"), so conversion fails loudly instead of
+// emitting a request the upstream is guaranteed to refuse.
+var ErrMissingMaxTokens = errors.New("claude messages request requires max_tokens: set max_tokens on the request or configure Options.Claude.DefaultMaxTokens")

relaykit/relayconvert/internal/shared/claude/schema.go

@@ -0,0 +1,16 @@
+package claude
+
+func FunctionParametersToInputSchema(parameters any) map[string]any {
+	params, _ := parameters.(map[string]any)
+	schema := make(map[string]any, len(params)+2)
+	for key, value := range params {
+		schema[key] = value
+	}
+	if schema["type"] == nil {
+		schema["type"] = "object"
+	}
+	if schema["properties"] == nil {
+		schema["properties"] = map[string]any{}
+	}
+	return schema
+}

relaykit/relayconvert/internal/shared/claude/tool_choice.go

@@ -0,0 +1,46 @@
+package claude
+
+import "github.com/QuantumNous/new-api/relaykit/dto"
+
+func MapOpenAIToolChoice(toolChoice any, parallelToolCalls *bool) *dto.ClaudeToolChoice {
+	var claudeToolChoice *dto.ClaudeToolChoice
+
+	if toolChoiceStr, ok := toolChoice.(string); ok {
+		switch toolChoiceStr {
+		case "auto":
+			claudeToolChoice = &dto.ClaudeToolChoice{
+				Type: "auto",
+			}
+		case "required":
+			claudeToolChoice = &dto.ClaudeToolChoice{
+				Type: "any",
+			}
+		case "none":
+			claudeToolChoice = &dto.ClaudeToolChoice{
+				Type: "none",
+			}
+		}
+	} else if toolChoiceMap, ok := toolChoice.(map[string]interface{}); ok {
+		if function, ok := toolChoiceMap["function"].(map[string]interface{}); ok {
+			if toolName, ok := function["name"].(string); ok {
+				claudeToolChoice = &dto.ClaudeToolChoice{
+					Type: "tool",
+					Name: toolName,
+				}
+			}
+		}
+	}
+
+	if parallelToolCalls != nil {
+		if claudeToolChoice == nil {
+			claudeToolChoice = &dto.ClaudeToolChoice{
+				Type: "auto",
+			}
+		}
+		if claudeToolChoice.Type != "none" {
+			claudeToolChoice.DisableParallelToolUse = !*parallelToolCalls
+		}
+	}
+
+	return claudeToolChoice
+}