[NO-ISSUE] feat(webkit): add Item inline kind, Item.List, and CardBox padded prop

[gab-az]

Summary

Extends the Item compound and CardBox to support the Figma "list of items in a card" and inline-on-page patterns.

• Item inline kind — new kind="inline" value that removes the row's outer padding (transparent surface); gap is preserved.
• Item.List (new sub-component, ./item-list) — divided in-card list: full-width bottom dividers between rows (--border-muted), no gap. Forces its items to the default kind so they never draw a per-item box inside the CardBox.
• Item.Group — now a gapped (--spacing-lg) off-card list that forces its items to inline, avoiding a box-in-box effect.
• CardBox padded prop (optional, default true) — pads the content region; set padded=false for flush, edge-to-edge content such as an Item.List.
• asChild interactivity — when asChild is set, the merged row (e.g. an anchor) now draws the focus-visible ring and hover/active ghost layers, so whole-row links are keyboard- and pointer-legible.

Notes

• Non-breaking. padded defaults to true, and the three CardBox consumers that pad their own content (onboarding-form, plan-success, deploy-success) were set to :padded="false" so they render identically. The CardBox Default story drops its inner padding to demonstrate the new default.
• Behavior change (not API-breaking): an Item placed inside Item.Group or Item.List has its kind coerced (to inline / default respectively) via a provided container context. Standalone Items are unaffected.
• No new runtime dependencies. Divider/gap/padding all use existing design tokens.
• Storybook: Item stories migrated to the canonical toSfc "Show code" source pattern and widened to w-full; added WithList, WithListAsChild, and Inline stories. Specs (item, card-box) updated with refreshed checksums.