修复Upload Service db_path重复问题

问题：
- FileTree::open_user_db(user_id)期望user_id参数
- 但server.rs中先调用user_db_path(user_id)，再传递db_path给open_user_db
- 导致路径重复：data/users/data/users/test_user.sqlite.sqlite

修复：
- extract_and_register_archive：直接传递user_id给init_user_db
- upload_file原始注册逻辑：直接传递user_id给init_user_db
- 使用init_user_db确保数据库表创建（file_registry）

测试验证：
- ZIP文件上传成功 ✅
- 自动解压成功（test_archive_extracted目录） ✅
- 提取文件正确（file1.txt, file2.txt, subdir/file3.txt） ✅
- 数据库初始化成功 ✅

markbase-core/src/server.rs

@@ -942,8 +942,7 @@ fn extract_and_register_archive(
         result.success_files, result.total_bytes);
     
     // Register extracted files to database
-    let db_path = FileTree::user_db_path(user_id);
+    let conn = FileTree::init_user_db(user_id)?;
-    let conn = FileTree::open_user_db(&db_path)?;
     
     let now = std::time::SystemTime::now()
         .duration_since(std::time::UNIX_EPOCH)
@@ -1196,15 +1195,15 @@ async fn upload_file(
     let hex = format!("{:x}", hash);
     let file_uuid = hex[0..32].to_string();
 
-    // Save to database (user-specific SQLite)
+// Save to database (user-specific SQLite)
-    let db_path = filetree::FileTree::user_db_path(&user_id);
     let file_uuid_clone = file_uuid.clone();
     let file_hash_clone = file_hash.clone();
     let filename_clone = filename.clone();
     let file_path_clone = file_path.clone();
+    let user_id_clone = user_id.clone();
     
     let db_result = tokio::task::spawn_blocking(move || -> anyhow::Result<()> {
-        let conn = filetree::FileTree::open_user_db(&db_path)?;
+        let conn = filetree::FileTree::init_user_db(&user_id_clone)?;
 
         // Register file
         let now = std::time::SystemTime::now()