test(RadarChart): verify language axis labels deduplicate for shared languages (JhaSourav07#2159)

## Description
Fixes JhaSourav07#1072

Adds a deduplication test to `RadarChart.test.tsx` that verifies when
both users share the same language (TypeScript), it appears as a single
axis label — not two separate axes.

- `languagesA` and `languagesB` both set to `[{ name: 'TypeScript', ...
}]`
- Asserts `getAllByText('TypeScript')` returns exactly 2 nodes (1 SVG
axis label + 1 stats table entry), confirming no duplicate axis is
rendered

## 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-only change, no SVG output modified.

## 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): ...`).
- [x] I have updated `README.md` if I added a new theme or URL
parameter. (N/A)
- [x] I have starred 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). (N/A —
test only)
- [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

components/dashboard/RadarChart.test.tsx

@@ -77,6 +77,17 @@ describe('RadarChart', () => {
     expect(screen.getAllByText('Python')).toBeDefined();
   });
 
+  it('deduplicates shared languages so TypeScript appears as a single axis label', () => {
+    const langsA = [{ name: 'TypeScript', percentage: 70, color: '#3178c6' }];
+    const langsB = [{ name: 'TypeScript', percentage: 50, color: '#3178c6' }];
+
+    render(<RadarChart languagesA={langsA} languagesB={langsB} labelA="User A" labelB="User B" />);
+
+    // TypeScript should appear exactly once as an axis label (SVG <text>) and once
+    // in the bottom stats table — 2 total, not 4 (which would indicate two separate axes)
+    expect(screen.getAllByText('TypeScript')).toHaveLength(2);
+  });
+
   it('scales axis points dynamically based on max score in data', () => {
     const highScoreLangs = [
       { name: 'TypeScript', percentage: 100, color: '#3178c6' },