Align STL Export Tower Grid with Real Weekdays

[ChetanSenta]

Description

Fixes #8315

Pillar

• 🎨 Pillar 1 — New Theme Design
• 📐 Pillar 2 — Geometric SVG Improvement
• 🕐 Pillar 3 — Timezone Logic Optimization
• 🛠️ Other

What this PR does

activityToTowers() (the 3D STL print export) derived each tower's grid
row from idx % 7 — the flat array index — rather than the day's
actual weekday. Every other tower-grid builder in the codebase
(computeTowers() in lib/svg/layout.ts, chunkDaysIntoWeeks() in
lib/calculate.ts) anchors rows to real, Sunday-first weekdays. This
made the exported 3D-printable model's grid pattern not match the same
user's actual 2D badge whenever the export's date range didn't happen to
start on a Sunday (the common case). Fixed by computing real weekday via
getUTCDay() and tracking week-column boundaries explicitly at real
Sunday transitions.

Changes

File	Change
lib/export3d.ts	activityToTowers() now derives row from getUTCDay() and increments col only at Sunday boundaries
lib/export3d.test.ts	New — verifies row=weekday alignment, correct week-column incrementing, and identical alignment regardless of the export's start-of-range weekday

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file.
• I have tested these changes locally.
• I have run npm run format and npm run lint locally and resolved all errors.
• My commits follow the Conventional Commits format.
• I have made sure that I have only one commit to merge in this PR.

[vercel]

Someone is attempting to deploy a commit to the jhasourav07's projects Team on Vercel.

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[retenta-bot]

This pull request addresses an important issue by aligning the STL export's tower grid with actual weekdays, which enhances the consistency of the exported models with the 2D badge representation. This change is crucial for users who rely on accurate date representations in their exports. Additionally, it includes new tests to verify the correct alignment and incrementing of week-columns.

It's worth noting that similar past decisions focused on enhancing timezone normalization and calendar boundary handling, which underscores the importance of accurate date calculations in our application. Thank you for your contribution, and I look forward to your updates!

[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	4052.60 KB	4052.50 KB	+0.10 KB (+0.00%)
Total CSS	338.94 KB	338.94 KB	0 B

[Aamod007]

Aligning the STL export tower grid with real weekdays — significant refactoring of the 3D export logic. CI failing, please fix.

Labels: level:intermediate (3 files, 167+93), quality:clean, type:bug, type:testing, mentor:Aamod007

[Aamod007]

Re-reviewing after noting the only CI failure is Vercel authorization (not code-related). All other checks (Format · Lint · Typecheck · Test, Production Build, CodeQL) pass. Approving — the Vercel deploy auth is a repo-level config issue, not a code problem.