[upstream] Tailwind v4 blocked by @lynx-js/tailwind-preset (v3-only)

[KealanAU]

@lynx-js/tailwind-preset only loads under Tailwind v3. Tailwind v4 reworked the preset/plugin model and is not compatible.

• Current pin: tailwindcss@^3.4.x everywhere (@vyui/kit, apps/examples/*)
• Blocked path: native Tailwind v4 in Lynx apps + @vyui/kit consumers

Mitigation today: docs site (apps/docs/) uses Tailwind v4 + Nuxt UI v4 — that's fine because it runs in the browser, not Lynx. Two Tailwind versions in the monorepo, unavoidable until upstream ships a v4-compatible preset.

Track until upstream lands a v4 preset.