[docs] Add brand logos marquee to docs homepage + misc papercuts

[christopherkindl]

Summary

• New brand-logos marquee section on the docs homepage (between ShopifyCommerce and the CTA), with edge-fade gradient via mask-image and a CSS-only horizontal scroll animation. Switched from a @theme inline animation token to @utility animate-marquee so Tailwind v4 reliably emits the class and keyframes.
• 6 new logo components (Ruggable, Bombas, Paige, AG1, Supreme, Made In) added under apps/docs/components/assets/logos/, following the existing logo conventions ({ height, className } props, currentColor fills, paths rounded to 3-decimal precision).
• Consolidated components/geistcn-fallbacks/geistcn-assets/ to components/assets/ and updated all 11 import sites.
• New AvatarTommy asset (components/assets/avatars/avatar-tommy.tsx) replacing the inline ▲ in the assistant demo.

Polish & fixes

• The outline button variant now bakes in the homepage's pill style (border-gray-alpha-400 bg-background-100 text-foreground shadow-none hover:bg-background-200); call sites in Hero / CTA / ShopifyCommerce drop their duplicate overrides. Fixes the missing dark-mode hover on the Hero "View Documentation" button.
• Assistant demo swaps "white" ↔ "black" sneaker via CSS-only dark:hidden / hidden dark:inline to match the existing dark/light product image swap.
• Agent demo: > → $ prompt symbol (consistent with content negotiation), spinner icon wrapped in a size-3.5 box with gap-2 so "Running skill…" aligns with $ / + / ~, log-lines use gap-2.5 for even vertical rhythm.
• Typing-line stability (agent + content negotiation demos): pinned line-box with leading-5, kept the cursor mounted (invisible instead of unmounted) with align-middle. Previously the inline-block cursor expanded the line-box during typing and the line shifted up by ~1px when typing finished.
• Minor responsive layout tweaks in centered-section, one-two-section, and fromsrc/footer.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
shop-docs	Ready	Preview, ✅ 5 resolved	May 5, 2026 2:18pm
shop-template	Ready	Preview, Comment, Open in v0	May 5, 2026 2:18pm

[vercel]

Additional Suggestion:

Button component variants "ghost" and "outline" were renamed to "tertiary" and "secondary" respectively, but 8 consuming files still reference the old variant names, causing a TypeScript build failure.