Add Store style variation (1.19.0)

[jasperf]

Summary

• New styles/store.json: cream page, charcoal text and dark bands, rust-orange brand colour, Cormorant Garamond display and Jost body, mapped onto all 12 palette-contract slugs plus terracotta and sand-deep.
• Self-hosted Cormorant Garamond and Jost variable fonts under assets/fonts/store/ (OFL 1.1, listed in readme.txt); loaded only when the style is active.
• Add-to-cart buttons use the small radius instead of the pill in this style.
• Version bump to 1.19.0 (style.css, package.json, readme.txt, CHANGELOG.md); CLAUDE.md notes the type-voice extension and the two checks every variation must pass.

Notes

• The orange is deliberately deep (#943A00): the Aludra night hero lifts its button fill toward white, and anything lighter drops that button under 4.5:1.
• Companion to Aludra 2.38.0's store patterns; works on any Aludra store homepage built from aludra/page-store-home.

Test plan

• Applied on the demo Aviendha subsite and checked with a scripted WCAG AA pass (4.5:1 text, 3:1 large) on the Aludra store homepage, /shop/ and a single product: 0 failures, desktop and mobile
• Visual check: homepage, shop archive, single product, mobile shop
• composer run lint
• Twilight is unaffected (separate file) — confirm it still applies after merge
• Cart, checkout and account pages not yet reviewed in this style

[jasperf]

Closing: the Store variation moves to Marin, a new e-commerce theme created from the Aviendha template (https://github.com/imagewize/marin).