feat(webkit): add the feature-card marketing component

[gabriel-lisboa-azion]

Summary

• One feature stated as a tile: an optional icon and overline, a short headline, a sentence of explanation, and — when there is somewhere to go — the whole tile as a link. It is the repeated unit of a marketing feature grid, and it is the marketing counterpart of card-box, which is a console container with header, content and footer regions.
• Public exports: @aziontech/webkit/feature-card.

How to test

1. pnpm storybook:dev → open Components/Marketing/FeatureCard. Every story renders, and "Show code" is a runnable SFC you can paste.
2. pnpm --filter @aziontech/webkit test -- src/components/marketing/feature-card → the co-located browser suite passes.
3. pnpm webkit:type-check → clean.

Notes

• No dependency on another marketing PR; it can merge in any order.
• Targets feature/marketing-components, which carries the shared foundation (marketing category registration, illustration scene registry, theme tokens, story assets).
• No breaking change: nothing is removed or renamed on main.

[gabriel-lisboa-azion]

Closing: feature-card was retired; padded glyph-and-link tiles are now topic in a CardGrid.Cell (#1018, #998). The branch is kept.