Production adapter wrapping a pdfrx PdfDocument: snapshots page sizes via the
real pdfrx 2.4.4 geometry API (PdfDocument.pages, PdfPage.width/height) so the
pure layout math runs on the real document. Because it lives under lib/editor/,
`flutter analyze lib/editor` (the Oracle) type-checks it against the installed
pdfrx every run — a version bump that renames/retypes these members now FAILS
analysis instead of silently drifting (SF4 source-pin, statically).
Runtime contract + layout composition tested via the pdfium-free .fromSizes
ctor; the .fromDocument pin is the static guarantee (exercising it needs pdfium
= device path).
flutter analyze lib/editor clean; 123/123 tests (+3).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
