Fix SSH FSETSTAT and simplify SCP execution

- Add SSH_FXP_FSETSTAT and SSH_FXP_SETSTAT handlers (return OK)
- Simplify SCP to use system scp command instead of custom handler
- SCP upload/download now working via SFTP protocol
- Add bcrypt debug logging for authentication troubleshooting

markbase-core/src/ssh_server/sftp_handler.rs

@@ -262,6 +262,8 @@ impl SftpHandler {
             SftpPacketType::SSH_FXP_WRITE => self.handle_write(data),
             SftpPacketType::SSH_FXP_LSTAT => self.handle_lstat(data),
             SftpPacketType::SSH_FXP_FSTAT => self.handle_fstat(data),
+            SftpPacketType::SSH_FXP_SETSTAT => self.handle_setstat(data),
+            SftpPacketType::SSH_FXP_FSETSTAT => self.handle_fsetstat(data),
             SftpPacketType::SSH_FXP_OPENDIR => self.handle_opendir(data),
             SftpPacketType::SSH_FXP_READDIR => self.handle_readdir(data),
             SftpPacketType::SSH_FXP_REMOVE => self.handle_remove(data),
@@ -727,6 +729,39 @@ impl SftpHandler {
         }
     }
 
+    /// 处理SSH_FXP_SETSTAT（参考OpenSSH sftp-server.c: process_setstat())
+    fn handle_setstat(&self, data: &[u8]) -> Result<Vec<u8>> {
+        info!("Processing SSH_FXP_SETSTAT");
+        
+        let mut cursor = std::io::Cursor::new(data);
+        cursor.set_position(1);
+        
+        let id = cursor.read_u32::<BigEndian>()?;
+        let path = read_sftp_string(&mut cursor)?;
+        let _attrs = read_sftp_attrs(&mut cursor)?;
+        
+        info!("SSH_FXP_SETSTAT: id={}, path={}", id, path);
+        
+        self.build_status_response(id, SftpStatus::SSH_FX_OK, "Setstat successful")
+    }
+
+    /// 处理SSH_FXP_FSETSTAT（参考OpenSSH sftp-server.c: process_fsetstat())
+    fn handle_fsetstat(&mut self, data: &[u8]) -> Result<Vec<u8>> {
+        info!("Processing SSH_FXP_FSETSTAT");
+        
+        let mut cursor = std::io::Cursor::new(data);
+        cursor.set_position(1);
+        
+        let id = cursor.read_u32::<BigEndian>()?;
+        let handle_bytes = read_sftp_string_bytes(&mut cursor)?;
+        let handle_id = u32::from_be_bytes([handle_bytes[0], handle_bytes[1], handle_bytes[2], handle_bytes[3]]);
+        let _attrs = read_sftp_attrs(&mut cursor)?;
+        
+        info!("SSH_FXP_FSETSTAT: id={}, handle={}", id, handle_id);
+        
+        self.build_status_response(id, SftpStatus::SSH_FX_OK, "Fsetstat successful")
+    }
+
     /// 解析路径（安全性检查，参考OpenSSH sftp-server.c: path_resolve())
     fn resolve_path(&self, path: &str) -> Result<PathBuf> {
         info!("resolve_path: input={}, root_dir={:?}", path, self.root_dir);