put: check the SFTP close status after uploads

ssh2::File's Drop discards the close-handshake error ('too late to
recover'), so a quota or server-side abort surfacing in the final ACKs
was recorded as a successful upload of a truncated file. Close upload
handles explicitly and propagate the error; also applies to the ssh
context driver's write_file and upload_recursive, which had the same
silent-drop issue.

src/put/ssh.rs

@@ -433,6 +433,16 @@ pub fn upload_file(
         bar.inc(n as u64);
     }
 
+    // Close explicitly: quota-exceeded and similar failures only surface in
+    // the final ACKs and the close handshake, and the `Drop` impl of
+    // `ssh2::File` discards that error ("too late to recover"), recording a
+    // truncated remote file as a successful upload. `ssh2::File::write` is
+    // unbuffered (`Write::flush` is a documented no-op) and `close`
+    // finalizes the pending writes server-side, so no flush is needed.
+    remote_file
+        .close()
+        .map_err(|e| format!("failed to close remote file '{remote}' after upload: {e}"))?;
+
     Ok(())
 }