feat: 添加 OCR 词汇提取功能

新增 OCR 页面，用户可上传教材词汇表截图，使用 GLM-4.6V 视觉模型
提取单词-释义对并保存到指定文件夹。

- AI 管道: src/lib/bigmodel/ocr/ (orchestrator, types)
- 后端模块: src/modules/ocr/ (action-service-repository 架构)
- 前端页面: src/app/(features)/ocr/ (拖拽上传、folder 选择)
- i18n: 8 种语言翻译支持

src/app/(features)/ocr/page.tsx

@@ -0,0 +1,20 @@
+import { OCRClient } from "./OCRClient";
+import { auth } from "@/auth";
+import { headers } from "next/headers";
+import { actionGetFoldersByUserId } from "@/modules/folder/folder-action";
+import { TSharedFolder } from "@/shared/folder-type";
+
+export default async function OCRPage() {
+  const session = await auth.api.getSession({ headers: await headers() });
+  
+  let folders: TSharedFolder[] = [];
+  
+  if (session?.user?.id) {
+    const result = await actionGetFoldersByUserId(session.user.id as string);
+    if (result.success && result.data) {
+      folders = result.data;
+    }
+  }
+
+  return <OCRClient initialFolders={folders} />;
+}