test(icons): add type compiler validation coverage (JhaSourav07#3123)

## Description

Adds TypeScript compiler validation coverage for
`app/components/Icons.tsx`.

This PR introduces a new `Icons.type-compiler.test.tsx` test suite that
verifies:

* icon exports remain function components
* icon components accept no parameters
* return types remain consistent across all exported icons
* exported typings remain stable

Fixes JhaSourav07#2822

## 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 (TypeScript compiler validation tests only)

## Checklist before requesting a review:

* [x] I have read the `CONTRIBUTING.md` file.
* [ ] 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.
* [ ] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
* [ ] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

app/components/Icons.type-compiler.test.tsx

@@ -0,0 +1,45 @@
+import { describe, expectTypeOf, it } from 'vitest';
+import { CopyIcon, ZapIcon, BoxIcon, CheckIcon, CloseIcon } from './Icons';
+
+describe('Icons Type Compiler Validation', () => {
+  it('exports icon components as functions', () => {
+    expectTypeOf(CopyIcon).toBeFunction();
+    expectTypeOf(ZapIcon).toBeFunction();
+    expectTypeOf(BoxIcon).toBeFunction();
+    expectTypeOf(CheckIcon).toBeFunction();
+    expectTypeOf(CloseIcon).toBeFunction();
+  });
+
+  it('accepts no parameters for icon components', () => {
+    expectTypeOf(CopyIcon).parameters.toEqualTypeOf<[]>();
+    expectTypeOf(ZapIcon).parameters.toEqualTypeOf<[]>();
+    expectTypeOf(BoxIcon).parameters.toEqualTypeOf<[]>();
+    expectTypeOf(CheckIcon).parameters.toEqualTypeOf<[]>();
+    expectTypeOf(CloseIcon).parameters.toEqualTypeOf<[]>();
+  });
+
+  it('all icon components return compatible types', () => {
+    expectTypeOf<ReturnType<typeof CopyIcon>>().toEqualTypeOf<ReturnType<typeof ZapIcon>>();
+
+    expectTypeOf<ReturnType<typeof ZapIcon>>().toEqualTypeOf<ReturnType<typeof BoxIcon>>();
+
+    expectTypeOf<ReturnType<typeof BoxIcon>>().toEqualTypeOf<ReturnType<typeof CheckIcon>>();
+
+    expectTypeOf<ReturnType<typeof CheckIcon>>().toEqualTypeOf<ReturnType<typeof CloseIcon>>();
+  });
+
+  it('maintains compatible return types across icons', () => {
+    expectTypeOf<ReturnType<typeof CopyIcon>>().toEqualTypeOf<ReturnType<typeof ZapIcon>>();
+
+    expectTypeOf<ReturnType<typeof BoxIcon>>().toEqualTypeOf<ReturnType<typeof CheckIcon>>();
+
+    expectTypeOf<ReturnType<typeof CheckIcon>>().toEqualTypeOf<ReturnType<typeof CloseIcon>>();
+  });
+
+  it('all icon components share the same callable signature', () => {
+    expectTypeOf(CopyIcon).toEqualTypeOf<typeof ZapIcon>();
+    expectTypeOf(ZapIcon).toEqualTypeOf<typeof BoxIcon>();
+    expectTypeOf(BoxIcon).toEqualTypeOf<typeof CheckIcon>();
+    expectTypeOf(CheckIcon).toEqualTypeOf<typeof CloseIcon>();
+  });
+});