test(copyrepobutton): add massive scaling test coverage (JhaSourav07#2973)

## Description

Fixes JhaSourav07#2804

Added massive scaling test coverage for `CopyRepoButton`.

### Tests Added

* Verifies rendering of large numbers of CopyRepoButton components
without crashing.
* Ensures button text remains consistent under heavy render loads.
* Confirms icons render correctly across many component instances.
* Validates repeated mounting does not throw errors.
* Checks large-scale button rendering behavior remains stable.

## Pillar

* [ ] 🎨 Pillar 1 — New Theme Design
* [ ] 📐 Pillar 2 — Geometric SVG Improvement
* [ ] 🕐 Pillar 3 — Timezone Logic Optimization
* [x] 🛠️ Other (Bug fix, refactoring, docs)

## Visual Preview

N/A (Test-only changes)

## Checklist before requesting a review:

* [x] I have read the `CONTRIBUTING.md` file.
* [x] I have tested these changes locally
(`localhost:3000/api/streak?user=YOUR_USERNAME`).
* [ ] I have run `npm run format` and `npm run lint` locally and
resolved all errors (CI will fail otherwise).
* [x] My commits follow the Conventional Commits format.
* [ ] I have updated `README.md` if I added a new theme or URL
parameter. (Not applicable)
* [x] I have starred the repo.
* [x] I have made sure that I have only one commit to merge in this PR.
* [ ] The SVG output matches the CommitPulse "premium quality" aesthetic
standard. (Not applicable)
* [ ] (Recommended) I joined the CommitPulse Discord community.

Author: JhaSourav07

app/components/CopyRepoButton.massive-scaling.test.tsx

@@ -0,0 +1,66 @@
+import { render, screen } from '@testing-library/react';
+import { describe, it, expect, vi } from 'vitest';
+import CopyRepoButton from './CopyRepoButton';
+
+vi.mock('lucide-react', () => ({
+  Copy: () => <svg data-testid="copy-icon" />,
+}));
+
+describe('CopyRepoButton Massive Scaling', () => {
+  it('renders 100 buttons without crashing', () => {
+    render(
+      <>
+        {Array.from({ length: 100 }).map((_, i) => (
+          <CopyRepoButton key={i} />
+        ))}
+      </>
+    );
+
+    expect(screen.getAllByText('Copy URL')).toHaveLength(100);
+  });
+
+  it('renders 500 buttons without layout break', () => {
+    render(
+      <>
+        {Array.from({ length: 500 }).map((_, i) => (
+          <CopyRepoButton key={i} />
+        ))}
+      </>
+    );
+
+    expect(screen.getAllByRole('button')).toHaveLength(500);
+  });
+
+  it('renders icon for every button under heavy load', () => {
+    render(
+      <>
+        {Array.from({ length: 200 }).map((_, i) => (
+          <CopyRepoButton key={i} />
+        ))}
+      </>
+    );
+
+    expect(screen.getAllByTestId('copy-icon')).toHaveLength(200);
+  });
+
+  it('maintains button text consistency across many renders', () => {
+    render(
+      <>
+        {Array.from({ length: 300 }).map((_, i) => (
+          <CopyRepoButton key={i} />
+        ))}
+      </>
+    );
+
+    const buttons = screen.getAllByText('Copy URL');
+    expect(buttons.length).toBe(300);
+  });
+
+  it('handles repeated mounting without throwing errors', () => {
+    expect(() => {
+      for (let i = 0; i < 50; i++) {
+        render(<CopyRepoButton />);
+      }
+    }).not.toThrow();
+  });
+});