test(HistoricalTrendView): add empty-fallback edge case tests

[Mahi11Patel]

Description

Fixes #4255

This PR adds the missing test file components/dashboard/HistoricalTrendView.empty-fallback.test.tsx as required by the issue.

The test file covers 5 edge cases for the HistoricalTrendView component when activity data is empty or missing:

• Renders without crashing when activity is an empty array
• Shows zero for all stats (contributions, active days, streak) on an empty dataset
• Displays the no-streak-data fallback message when activity is empty
• Displays monthly and yearly empty-state messages when there is no activity
• Renders the period label and navigation controls even with no activity data

All 5 tests pass with vitest run.

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 file only, no SVG changes

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.

[Mahi11Patel]

Hi @JhaSourav07 ,
I've completed this PR and all CI checks are passing. When you have time, could you please review it? Thank you!

[github-actions]

📦 Next.js Bundle Size Report (Gzipped Sizes)

✨ No significant bundle size changes detected.

📊 Summary of Totals

Category	PR Size	Base Size	Difference
Total JS	3433.84 KB	3433.84 KB	0 B
Total CSS	258.05 KB	258.05 KB	0 B

[Aamod007]

Good fallback coverage here. The updated components/dashboard/HistoricalTrendView.empty-fallback.test.tsx and the new components/AnimatedCursor.empty-fallback.test.tsx cover the empty activity state, period/navigation controls, and cursor fallback behavior without changing production code, so this is a clean test-only addition.