[FEATURE]: Copy Button doesn't work in HTTP - Use `document.execCommand("copy")` as fallback

[Hashory]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Currently, the Copy button does not work in http environments because the navigator.clipboard API requires a secure context (https or localhost).

Many opencode users likely run the application in self-hosted http contexts, so this limits usability.

Although document.execCommand("copy") is deprecated, it is still supported by many browsers and works in http enviroments.
I propose implementing execCommand as a fallback when navigator.clipboard is unavalible.

Sample Code

const content = "copy content";

// Check if clipboard API is available
if (navigator.clipboard && navigator.clipboard.writeText) {
  navigator.clipboard.writeText(content);
} else {
  // Fallback for HTTP / older browsers
  const textarea = document.createElement("textarea");
  textarea.value = content;
  document.body.appendChild(textarea);
  textarea.select();
  document.execCommand("copy");
  document.body.removeChild(textarea);
}

[Hastyshell]

I ran into the same issue and it has been bothering me in my daily work, so I tried to submit a PR #17549 to address it.
I'm not very experienced with frontend, so if anyone is interested, I'd really appreciate it if you could take a look.