test: add responsive breakpoint tests for stats route

[AMAN194701]

Description

Closes #6784

Added a dedicated responsive breakpoint test suite for the Stats route.

Changes

• Added app/api/stats/route.responsive-breakpoints.test.ts
• Implemented 5 responsive breakpoint test cases covering:
  • Standard mobile-width viewport (375px)
  • Responsive multi-device column layouts
  • Vertical column reflow
  • Prevention of horizontal overflow on small viewports
  • Mobile-specific navigation/toggle behavior
• Verified all tests pass successfully using Vitest.

Pillar

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

Visual Preview

N/A (Test-only changes)

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file..
• My commits follow the Conventional Commits format (e.g., feat(themes): ..., fix(calculate): ...).
• I have starred the repo.
• I have made sure that I have only one commit to merge in this PR.

[github-actions]

🚨 Hey @AMAN194701, the CI Pipeline is failing on this PR and it has been marked as status:blocked.

Please fix the issues before this can be reviewed. Here's how:

1. Run checks locally before pushing:

npm run format:check   # Check Prettier formatting
npm run lint           # Run ESLint
npm run typecheck      # TypeScript type check
npm run test           # Run unit tests (Vitest)
npm run build          # Verify production build passes

2. Auto-fix common issues:

npm run format         # Auto-fix formatting with Prettier
npm run lint -- --fix  # Auto-fix lint errors where possible

3. Check the full failure log here:
👉 View CI Run

Once you push a fix and the CI passes, the status:blocked label will be removed automatically. 💪

[Aamod007]

Good job implementing the responsive breakpoint tests for the stats API route. However, the Vercel check is failing. Please resolve the issues and rerun the CI pipeline.

[Aamod007]

Upon re-evaluation, I realized I previously misinterpreted the Vercel deployment failure as an issue with this PR. The Vercel build failure seems unrelated to the changes introduced here, so I will ignore it moving forward. The rest of the PR looks good, so I'm approving it!