pass button classname instead of icon classname to fix padding (#7006)

## 📝 Summary

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Provide a concise summary of what this pull request is addressing.

If this PR fixes any issues, list them here by number (e.g., Fixes
#123).
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the copy button was taking up unecessary padding, because the styles
were applied to the icon, not the button.

before:
![CleanShot 2025-10-31 at 00 25
34](https://github.com/user-attachments/assets/290aa70a-4acb-4834-aa1f-c8ef0163d517)

after:
![CleanShot 2025-10-31 at 00 27
36](https://github.com/user-attachments/assets/e9eedb10-9246-4792-ad78-f74b30beedc8)


## 🔍 Description of Changes

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problem addressed and how it was resolved. If applicable, provide before
and after comparisons, screenshots, or any relevant details to help
reviewers understand the changes easily.
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## 📋 Checklist

- [x] I have read the [contributor
guidelines](https://github.com/marimo-team/marimo/blob/main/CONTRIBUTING.md).
- [ ] For large changes, or changes that affect the public API: this
change was discussed or approved through an issue, on
[Discord](https://marimo.io/discord?ref=pr), or the community
[discussions](https://github.com/marimo-team/marimo/discussions) (Please
provide a link if applicable).
- [x] I have added tests for the changes made.
- [x] I have run the code and verified that it works as expected.

Author: Light2Dark

frontend/src/components/icons/copy-icon.tsx

@@ -11,6 +11,7 @@ import { toast } from "../ui/use-toast";
 interface Props {
   value: string | ((event: React.MouseEvent) => string);
   className?: string;
+  buttonClassName?: string;
   tooltip?: React.ReactNode | false;
   toastTitle?: string;
   ariaLabel?: string;
@@ -19,6 +20,7 @@ interface Props {
 export const CopyClipboardIcon: React.FC<Props> = ({
   value,
   className,
+  buttonClassName,
   tooltip,
   toastTitle,
   ariaLabel,
@@ -41,6 +43,7 @@ export const CopyClipboardIcon: React.FC<Props> = ({
       type="button"
       onClick={handleCopy}
       aria-label={ariaLabel ?? "Copy to clipboard"}
+      className={buttonClassName}
     >
       {isCopied ? (
         <CheckIcon className={cn(className, "text-(--grass-11)")} />

frontend/src/plugins/impl/code/any-language-editor.tsx

@@ -58,7 +58,8 @@ const AnyLanguageCodeMirror: React.FC<
       {showCopyButton && !isNotSupported && (
         <CopyClipboardIcon
           tooltip={false}
-          className="absolute top-2 right-2 p-1 hover-action z-10 text-muted-foreground"
+          buttonClassName="absolute top-2 right-2 z-10 hover-action"
+          className="h-4 w-4 text-muted-foreground"
           value={props.value || ""}
           toastTitle="Copied to clipboard"
         />