test(calculate): verify streak formulas for different starting days of the week timeline (Variation 2) (#1486)

[boss477]

Description

This PR adds test coverage to verify the streak formulas when commits are made starting on different days of the week (specifically starting on Wednesday), acting as Variation 2 of the starting days timeline tests.

Fixes #1486

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 (Tests only)

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file.
• I have tested these changes locally (localhost:3000/api/streak?user=boss477).
• 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 starred 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]

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[github-actions]

👋 Hey @boss477, it looks like you didn't use our PR template!

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Please update your PR description to include all required sections so we can review this properly:

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[github-actions]

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