Measure adoption of PDF print options before keeping the color picker

[aalemayhu]

PR #2296 added four user-configurable options to the PDF export flow (background color, paper size, orientation, margins). PR #2297 polished the color swatch.

PM's read at merge: the color picker is the most gold-plated of the four — full hex range when most users will print on white paper. Keeping it on instinct, not data.

Decision rule

If <5% of paying users who hit POST /api/apkg/pdf send a non-default value (backgroundColor !== '#ffffff') within 30 days of this issue being filed, revert the color picker from PrintForm.tsx and the backgroundColor field from parsePdfOptions / buildHtml. Paper size, orientation, and margins stay regardless.

What to instrument

• Per-request: which of the four options differ from the default (A4 / portrait / normal / #ffffff). Server-side, in ApkgController.exportPdf after parsePdfOptions returns.
• Aggregate weekly into the existing observability path (whatever the closest equivalent of the services/observability exporter is for this kind of feature-usage signal — pick the lightest one that already exists; do not stand up a new pipeline).

Review

Check back 2026-06-14. If color-picker usage is below the bar, open a revert PR.