feat: 重构配置管理，使用数据库替代环境变量，优化系统配置读取

server/utils/openai.ts

@@ -1,8 +1,6 @@
 // server/utils/openai.ts - OpenAI Chat Completions 流式调用工具
-import { serverEnv } from "~~/server/utils/env";
+import { getSysConfig } from "~~/server/utils/sysConfig";
 
-/** 旧项目的 `OPENAI_API_BASE` 语义是完整 base，例如 `https://api.openai.com/v1` */
-const CHAT_COMPLETIONS_URL = `${serverEnv.openAiApiBase}/chat/completions`;
 /** 复用编码器计算 SSE data 字节长度，避免循环里频繁创建对象 */
 const textEncoder = new TextEncoder();
 
@@ -56,21 +54,25 @@ export const askAnswerStream = async ({
   prompt: string;
   systemPrompt: string;
 }): Promise<AskAnswerStreamResult> => {
-  if (!serverEnv.openAiApiKey) {
+  const cfg = await getSysConfig();
+
+  if (!cfg.openAiApiKey) {
     throw new Error("OPENAI_API_KEY is not set.");
   }
 
+  const chatCompletionsUrl = `${cfg.openAiApiBase}/chat/completions`;
+
   // 这里不要记录 request body：其中包含完整题目和可能的选项文本
-  const response = await fetch(CHAT_COMPLETIONS_URL, {
+  const response = await fetch(chatCompletionsUrl, {
     method: "POST",
     headers: {
-      Authorization: `Bearer ${serverEnv.openAiApiKey}`,
+      Authorization: `Bearer ${cfg.openAiApiKey}`,
       "Content-Type": "application/json"
     },
     body: JSON.stringify({
-      model: serverEnv.openAiModel,
-      temperature: serverEnv.temperature,
-      max_tokens: serverEnv.maxTokens,
+      model: cfg.openAiModel,
+      temperature: cfg.temperature,
+      max_tokens: cfg.maxTokens,
       stream: true,
       messages: [
         {
@@ -94,7 +96,10 @@ export const askAnswerStream = async ({
   }
 
   // 将 SSE delta 读完后再返回给 API handler，由 handler 统一做答案清洗和缓存
-  const upstreamResponse = await readChatCompletionStream(response.body);
+  const upstreamResponse = await readChatCompletionStream(
+    response.body,
+    cfg.maxSseLineBytes
+  );
 
   return {
     answer: upstreamResponse.content.trim(),
@@ -112,7 +117,8 @@ export const askAnswerStream = async ({
  * 网络 chunk 不一定按行对齐，所以用 buffer 保存尚未拼完整的一行
  */
 export const readChatCompletionStream = async (
-  stream: ReadableStream<Uint8Array>
+  stream: ReadableStream<Uint8Array>,
+  maxSseLineBytes: number
 ): Promise<ChatCompletionStreamResult> => {
   const reader = stream.getReader();
   const decoder = new TextDecoder();
@@ -146,14 +152,14 @@ export const readChatCompletionStream = async (
 
     // stream: true 可以正确处理跨 chunk 的多字节字符，例如中文
     buffer += decoder.decode(value, { stream: true });
-    assertSseBufferSize(buffer, serverEnv.maxSseLineBytes);
+    assertSseBufferSize(buffer, maxSseLineBytes);
 
     // 只处理已经遇到换行的完整 SSE 行，最后一段留到下次 chunk 再拼
     const lines = buffer.split(/\r?\n/u);
     buffer = lines.pop() ?? "";
 
     for (const line of lines) {
-      const chunk = parseSseDataLine(line, serverEnv.maxSseLineBytes);
+      const chunk = parseSseDataLine(line, maxSseLineBytes);
       if (chunk) collectChunk(chunk);
     }
   }
@@ -161,7 +167,7 @@ export const readChatCompletionStream = async (
   // 处理流结束时仍留在 buffer 中的最后一行
   const finalText = buffer + decoder.decode();
   for (const line of finalText.split(/\r?\n/u)) {
-    const chunk = parseSseDataLine(line, serverEnv.maxSseLineBytes);
+    const chunk = parseSseDataLine(line, maxSseLineBytes);
     if (chunk) collectChunk(chunk);
   }