Uploaded signatures/stamps aren't always transparent PNGs, so an opaque stamp
overlapping the signature/name would cover them. Extract the signatory-block
geometry into a tested helper (signatoryLayout): the signature is centred over
the name and the stamp sits to its RIGHT with a 10px gap — never overlapping.
- lib/po-export-layout.ts (signatoryLayout) + unit test
- export route uses it instead of inline overlap math
Verified in a real export: signature 175-328px (centred), stamp 338-405px
(10px gap, no overlap), stamp drawn behind the signature.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
