feat: 添加注册开关功能，优化系统配置与注册接口

server/utils/sysConfig.ts

@@ -17,6 +17,8 @@ export interface SysConfig {
   temperature: number;
   /** 单行 SSE data 最大字节数，防止异常流无限堆内存 */
   maxSseLineBytes: number;
+  /** 是否允许新用户注册；false 时注册接口直接拒绝 */
+  allowRegistration: boolean;
 }
 
 // system_config 表 key 字段的常量映射
@@ -26,7 +28,8 @@ const CONFIG_KEYS = {
   openAiModel: "openai_model",
   maxTokens: "max_tokens",
   temperature: "temperature",
-  maxSseLineBytes: "openai_stream_max_sse_line_bytes"
+  maxSseLineBytes: "openai_stream_max_sse_line_bytes",
+  allowRegistration: "allow_registration"
 } as const;
 
 // 硬编码默认值，与原 env.ts 的 fallback 保持一致
@@ -36,7 +39,9 @@ const DEFAULTS: SysConfig = {
   openAiModel: "gpt-5.2",
   maxTokens: 500,
   temperature: 0.7,
-  maxSseLineBytes: 1_048_576
+  maxSseLineBytes: 1_048_576,
+  // 默认开放注册；管理员可通过系统配置关闭
+  allowRegistration: true
 };
 
 // 内存缓存：减少每请求查 DB 的开销
@@ -82,7 +87,10 @@ export const getSysConfig = async (): Promise<SysConfig> => {
     openAiModel: str(CONFIG_KEYS.openAiModel, DEFAULTS.openAiModel),
     maxTokens: int(CONFIG_KEYS.maxTokens, DEFAULTS.maxTokens),
     temperature: float(CONFIG_KEYS.temperature, DEFAULTS.temperature),
-    maxSseLineBytes: int(CONFIG_KEYS.maxSseLineBytes, DEFAULTS.maxSseLineBytes)
+    maxSseLineBytes: int(CONFIG_KEYS.maxSseLineBytes, DEFAULTS.maxSseLineBytes),
+    // "true" 以外的值均视为关闭；空值（未设置）走默认值 true
+    allowRegistration:
+      (map.get(CONFIG_KEYS.allowRegistration) ?? "true") !== "false"
   };
 
   _cachedConfig = config;
@@ -144,7 +152,9 @@ export const getUserEffectiveApiConfig = async (
     openAiModel: customModel.length > 0 ? customModel : sysCfg.openAiModel,
     maxTokens: userConfig.customMaxTokens ?? sysCfg.maxTokens,
     temperature: userConfig.customTemperature ?? sysCfg.temperature,
-    maxSseLineBytes: sysCfg.maxSseLineBytes
+    maxSseLineBytes: sysCfg.maxSseLineBytes,
+    // 用户有效配置不改变注册开关，手带系统值
+    allowRegistration: sysCfg.allowRegistration
   };
 };