test(streak): Adds text colour parameter route tests (JhaSourav07#600)

## Description
Adds two missing test cases for the '?text=' query parameter in the
streak route:
->Asserts that '?text=ff0000' causes the hex '#ff0000' to appear in the
SVG body.
->Asserts that an invalid text value does not crash the route and falls
back without crashing.
Fixes JhaSourav07#355

## Pillar

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

## Visual Preview
No visual changes — this PR only adds tests.
## 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.
- [ ] 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: Ishanvee

app/api/streak/route.test.ts

@@ -339,6 +339,19 @@ describe('GET /api/streak', () => {
 
       expect(body).toContain('#00ff00');
     });
+
+    it('embeds a custom text color in the SVG when text is provided', async () => {
+      const response = await GET(makeRequest({ user: 'octocat', text: 'ff0000' }));
+      const body = await response.text();
+
+      expect(body).toContain('#ff0000');
+    });
+
+    it('does not crash when an invalid text color is provided', async () => {
+      const response = await GET(makeRequest({ user: 'octocat', text: 'notacolor' }));
+
+      expect(response.status).toBe(200);
+    });
   });
 
   describe('error handling', () => {