test: add disabled state coverage for Watch Dashboard link

[kanishka-2007-tech]

Description

The Watch Dashboard link in app/page.tsx uses aria-disabled={!hasUsername} to prevent navigation when no username is provided. The disabled state behavior was not previously covered by tests.

Changes Made

• Added test coverage for the disabled state of the Watch Dashboard link.
• Verified the link has aria-disabled="true" when the username input is empty.
• Verified the disabled state is removed after entering a valid username.
• Ensured existing page tests continue to pass.

Test Scenarios

• Render the page with an empty username and verify the Watch Dashboard link is disabled.
• Enter a username and verify the disabled state is removed.

Fixes #709

Pillar

• 📐 Pillar 2 — Geometric SVG Improvement
• 🛠️ Other (Bug fix, refactoring, docs)

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file.
• I have tested these changes locally (localhost:3000/api/streak?user=YOUR_USERNAME).
• I have run npm run format and npm run lint locally and resolved all errors (CI will fail otherwise).
• 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.
• I have started the repo.
• 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).
• (Recommended) I joined the CommitPulse Discord community for contributor discussions, mentorship, and faster PR support.

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[github-actions]

🚨 Hey @kanishka-2007-tech, 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. 💪

[github-actions]

⚠️ Hey @kanishka-2007-tech, this PR has merge conflicts with the main branch.

Please pull the latest changes and resolve the conflicts so we can review it!

git fetch origin
git rebase origin/main
# resolve any conflicts, then:
git push --force-with-lease

Once resolved, the needs-rebase label will be removed automatically on the next check. 🙌