test(Icons-theme-contrast): verify Dark and Light Prefers-Color-Scheme Visual Cohesion (Variation 3) (JhaSourav07#3113)

## Description

This PR implements testing to verify Dark and Light
`prefers-color-scheme` visual cohesion for the `Icons` component. It
ensures that standard icons dynamically adapt to the application's theme
using `currentColor`, while validating that the `CheckIcon` strictly
retains its semantic green success color (`#10b981`) across both dark
and light themes.

Fixes JhaSourav07#2815

## 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 addition only, no visual 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`).
- [x] 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 (e.g.,
`feat(themes): ...`, `fix(calculate): ...`).
- [ ] I have updated `README.md` if I added a new theme or URL
parameter.
- [x] I have started the repo.
- [x] I have made sure that i have only one commit to merge in this PR.
- [x] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
- [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

app/components/Icons.theme-contrast.test.tsx

@@ -0,0 +1,39 @@
+import { render } from '@testing-library/react';
+import { describe, expect, it } from 'vitest';
+
+import { BoxIcon, CheckIcon, CloseIcon, CopyIcon, ZapIcon } from './Icons';
+
+describe('Icons theme contrast behavior', () => {
+  it('renders CheckIcon with fixed semantic color for success state', () => {
+    const { container } = render(<CheckIcon />);
+    const svg = container.querySelector('svg');
+    // Verifies the icon maintains visual cohesion by using a fixed color
+    // that works well in both light and dark modes
+    expect(svg?.getAttribute('stroke')).toBe('#10b981');
+  });
+
+  it('renders CopyIcon with inherited color for theme adaptability', () => {
+    const { container } = render(<CopyIcon />);
+    const svg = container.querySelector('svg');
+    // Verifies the icon uses currentColor to adapt to parent theme context
+    expect(svg?.getAttribute('stroke')).toBe('currentColor');
+  });
+
+  it('renders ZapIcon with inherited color for theme adaptability', () => {
+    const { container } = render(<ZapIcon />);
+    const svg = container.querySelector('svg');
+    expect(svg?.getAttribute('stroke')).toBe('currentColor');
+  });
+
+  it('renders BoxIcon with inherited color for theme adaptability', () => {
+    const { container } = render(<BoxIcon />);
+    const svg = container.querySelector('svg');
+    expect(svg?.getAttribute('stroke')).toBe('currentColor');
+  });
+
+  it('renders CloseIcon with inherited color for theme adaptability', () => {
+    const { container } = render(<CloseIcon />);
+    const svg = container.querySelector('svg');
+    expect(svg?.getAttribute('stroke')).toBe('currentColor');
+  });
+});