test(dashboard): expand generateMetadata Open Graph assertions (JhaSourav07#784)

## Description

Fixes JhaSourav07#706

Expanded the `generateMetadata` test coverage in
`app/(root)/dashboard/[username]/page.test.tsx` by adding assertions for
additional Open Graph and Twitter metadata fields.

## Pillar

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

## Visual Preview

Not applicable — this PR only expands metadata test coverage.

## 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 test` locally and resolved all errors.
* [x] My commits follow the Conventional Commits format.
* [ ] 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] All existing page tests pass successfully.
* [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

## Changes Made

Added assertions for:

* `openGraph.images[0].width === 1200`
* `openGraph.images[0].height === 630`
* `openGraph.images[0].alt` contains the username
* `twitter.card === 'summary_large_image'`

Author: Vishvadharman

app/(root)/dashboard/[username]/page.test.tsx

@@ -61,7 +61,6 @@ vi.mock('@/components/dashboard/Achievements', () => ({
   default: () => <div data-testid="achievements">Achievements</div>,
 }));
 
-// ADD THIS
 vi.mock('@/components/dashboard/RefreshButton', () => ({
   default: () => <div data-testid="refresh-button">RefreshButton</div>,
 }));
@@ -102,13 +101,20 @@ describe('DashboardPage', () => {
 
   describe('generateMetadata', () => {
     it('generates correct metadata for a given user', async () => {
+      const username = 'octocat';
       const metadata = await generateMetadata({
-        params: Promise.resolve({ username: 'octocat' }),
+        params: Promise.resolve({ username }),
       });
 
+      const openGraphImage = (metadata.openGraph?.images as any[])?.[0];
+
       expect(metadata.title).toBe("octocat's Commit Pulse");
       expect(metadata.description).toContain("octocat's GitHub contribution pulse");
-      expect((metadata.openGraph?.images as any[])?.[0].url).toContain('api/og?username=octocat');
+      expect(openGraphImage.url).toContain('api/og?username=octocat');
+      expect(openGraphImage.width).toBe(1200);
+      expect(openGraphImage.height).toBe(630);
+      expect(openGraphImage.alt).toContain(username);
+      expect((metadata.twitter as any)?.card).toBe('summary_large_image');
     });
   });