refactor: 使用 openai SDK 替换 fetch 调用 LLM

- 安装 openai 包
- 重命名 zhipu.ts -> llm.ts
- 使用 OpenAI SDK 替代原生 fetch 实现
- 更新所有导入路径

pnpm-lock.yaml

@@ -45,6 +45,9 @@ importers:
       nodemailer:
         specifier: ^8.0.2
         version: 8.0.2
+      openai:
+        specifier: ^6.27.0
+        version: 6.27.0(zod@4.3.5)
       pg:
         specifier: ^8.16.3
         version: 8.16.3
@@ -2731,6 +2734,18 @@ packages:
     resolution: {integrity: sha512-YgBpdJHPyQ2UE5x+hlSXcnejzAvD0b22U2OuAP+8OnlJT+PjWPxtgmGqKKc+RgTM63U9gN0YzrYc71R2WT/hTA==}
     engines: {node: '>=18'}
 
+  openai@6.27.0:
+    resolution: {integrity: sha512-osTKySlrdYrLYTt0zjhY8yp0JUBmWDCN+Q+QxsV4xMQnnoVFpylgKGgxwN8sSdTNw0G4y+WUXs4eCMWpyDNWZQ==}
+    hasBin: true
+    peerDependencies:
+      ws: ^8.18.0
+      zod: ^3.25 || ^4.0
+    peerDependenciesMeta:
+      ws:
+        optional: true
+      zod:
+        optional: true
+
   optionator@0.9.4:
     resolution: {integrity: sha512-6IpQ7mKUxRcZNLIObR0hz7lxsapSSIYNZJwXPGeF0mTVqGKFIXj1DQcMoT22S3ROcLyY/rz0PWaWZ9ayWmad9g==}
     engines: {node: '>= 0.8.0'}
@@ -6162,6 +6177,10 @@ snapshots:
       is-inside-container: 1.0.0
       wsl-utils: 0.1.0
 
+  openai@6.27.0(zod@4.3.5):
+    optionalDependencies:
+      zod: 4.3.5
+
   optionator@0.9.4:
     dependencies:
       deep-is: 0.1.4