Previous behavior silently deleted static/shopping/*.svg when
SHOPPING_*_NUMBER env vars were unset, then rsync --delete propagated
the deletion to the prod server — the loyalty buttons disappeared on
deploys where the env didn't reach the build (or during the brief
rm→write window of a parallel run).
Now the script exits non-zero with a clear message; deploy.sh's set -e
aborts before any destructive sync.
Coop Supercard uses GS1 Data Matrix — the payload contains FNC1
separators between fields, not literal 0x1D bytes. Enable bwip-js
parsefnc so ^FNC1 placeholders in the env value produce genuine
FNC1 codewords (codeword 232), matching the physical card and
letting checkout scanners parse the GS1 element string.
Adds a CreditCard button on the shopping list that opens a modal
showing the user's Coop Supercard (Data Matrix) and Migros Cumulus
(Code 128). Card numbers come from SHOPPING_COOP_SUPERCARD_NUMBER
and SHOPPING_MIGROS_CUMULUS_NUMBER env vars; a prebuild script
renders each to an SVG (~1-2 kB) in static/shopping/ so no barcode
library ships to the client. Cards missing their env var are
silently skipped, and the generated SVGs are gitignored to keep
personal numbers out of the repo.
Alexander
