Add OTP QR import from TOTP and entry editors (#120)

crates/storage/tests/presentation.rs

@@ -260,6 +260,12 @@ fn qr_image_import_returns_secret_bytes_and_rejects_invalid_input() -> TestResul
     image.write_to(&mut encoded, image::ImageFormat::Png)?;
     let decoded = QrMatrix::decode_image(&SecretBytes::new(encoded.into_inner()))?;
     assert_eq!(decoded.expose(), payload.expose());
+    let mut oversized = Cursor::new(Vec::new());
+    image::GrayImage::new(4097, 1).write_to(&mut oversized, image::ImageFormat::Png)?;
+    assert!(matches!(
+        QrMatrix::decode_image(&SecretBytes::new(oversized.into_inner())),
+        Err(QrError::InvalidImage)
+    ));
     assert!(matches!(
         QrMatrix::decode_image(&SecretBytes::new(b"not an image".to_vec())),
         Err(QrError::InvalidImage)