Three enhancements requested by @oliboehm after the V1 label-printing
ship in #809:
- New box_40x30 single-label template (common DK/Brother roll size,
good for filament-bag and storage-bin labels). Routes through the
existing roomy layout since height >= 20 mm.
- Colour hex code (#RRGGBB, alpha-stripped, uppercase) rendered on
every label - useful when several near-identical material/colour
spools sit next to each other and the swatch alone isn't enough to
tell them apart. Skipped silently when rgba is None or malformed.
- Brand line bumped to Helvetica-Bold (was regular) and a couple of
points larger on both layouts so it reads cleanly at arm's length.
Wired through the SpoolLabelTemplate union, the modal's
TEMPLATE_OPTIONS, and the inventory.labels.templates.box40x30 i18n
key in all 8 locales (native translations for de/fr/it/ja/pt-BR/
zh-CN/zh-TW). Modal regression test widened from 4 to 5 template
buttons. Three new renderer tests pin the hex-code render, the
hex-code skip on invalid rgba, and the bold-brand font reference.