fix: support vertical carousel arrow keys

[codejupiter]

Summary

• Updates Base UI and Radix carousel keyboard handling so vertical carousels respond to ArrowUp / ArrowDown.
• Keeps horizontal carousel behavior on ArrowLeft / ArrowRight.
• Regenerates the v4 style registry outputs.

Why

Vertical carousels should use directional keys that match their axis. Before this change, the handler only listened for left/right keys regardless of orientation, so orientation="vertical" carousels ignored the natural up/down keyboard controls.

Fixes #10219.

Validation

• npx -y pnpm@9.0.6 --filter=shadcn build
• npx -y bun@latest run ./scripts/build-registry.mts from apps/v4
• npx -y pnpm@9.0.6 --filter=v4 validate:registries
• npx -y pnpm@9.0.6 --filter=v4 typecheck
• npx -y pnpm@9.0.6 --filter=v4 lint
• npx -y pnpm@9.0.6 --filter=v4 format:check
• git diff --check

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