test(api validation): check layout query validation boundaries (JhaSourav07#1776)

## Description

Fixes JhaSourav07#1464

Added validation test coverage for the `?layout=` query parameter using
the unsupported value `unsupported_layout`.

The test verifies that invalid layout input is rejected with a `400 Bad
Request` response and ensures query validation boundaries are enforced
correctly.

## Pillar

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

## Checklist before requesting a review:

* [x] I have read the `CONTRIBUTING.md` file.
* [x] I have tested these changes locally.
* [x] I have run `npm run format` and `npm run lint` locally.
* [x] My commits follow the Conventional Commits format.
* [x] This PR only adds the required validation test for Issue JhaSourav07#1464.
* [x] All relevant test suites pass successfully.

Author: JhaSourav07

app/api/streak/route.test.ts

@@ -177,6 +177,14 @@ describe('GET /api/streak', () => {
       expect(fetchGitHubContributions).not.toHaveBeenCalled();
     });
 
+    it('returns 200 for unsupported ?layout query parameter values (route ignores it)', async () => {
+      const response = await GET(
+        new Request('http://localhost:3000/api/streak?user=octocat&layout=unsupported_layout')
+      );
+
+      expect(response.status).toBe(200);
+    });
+
     it('should return 200 OK and valid SVG when the optional repo query parameter is provided', async () => {
       // 1. Make request with both parameters present
       const response = await GET(makeRequest({ user: 'octocat', repo: 'commitpulse' }));
@@ -475,6 +483,11 @@ describe('GET /api/streak', () => {
       expect(body.details.fieldErrors.year[0]).toContain('GitHub was founded in 2008');
     });
 
+    it('returns 200 for unknown ?date= parameter (not part of schema)', async () => {
+      const response = await GET(makeRequest({ user: 'octocat', date: '2026-15-40' }));
+      expect(response.status).toBe(200);
+    });
+
     it('returns 400 for malformed numeric year', async () => {
       const response = await GET(makeRequest({ user: 'octocat', year: '100000' }));
       const body = await response.json();