message: Add "Copied!" feedback to `copy-file` button
diff: @@ -11,6 +11,13 @@ function handleClick({currentTarget: button}: React.MouseEvent<HTMLButtonElement
  .map(({innerText: line}) => line === '\n' ? '' : line) // Must be `.innerText`
  .join('\n');
  copyToClipboard(content);
  +
  + button.textContent = 'Copied!';
  + button.classList.remove('tooltipped');
  + setTimeout(() => {
  + button.textContent = 'Copy';
  + button.classList.add('tooltipped');
  + }, 2000);
  }
  function renderButton(): void {
  