The old getPdfPageCount used a fragile regex on raw PDF binary that
could undercount pages, causing survey sides to be skipped entirely.
Replaced with pdf-lib's PDFDocument.load() for reliable counting,
with the old regex as a fallback.
Added logging for page counts and pairing to diagnose missing backs.
Made-with: Cursor
Duplex scanners flip the sheet between sides, so odd pages (back) are
180° rotated relative to even pages (front). Landscape back pages now
rotate CCW instead of CW, and portrait back pages get a 180° flip.
Also swapped "Front"/"Back" labels to match the physical card sides.
Made-with: Cursor
Scanners store landscape content with a PDF /Rotate flag that pdf2pic
doesn't always apply. Now uses a square bounding box with
preserveAspectRatio, then detects landscape output and rotates to
portrait with sharp.
Made-with: Cursor
