feat: Add instiution name to layout for DataKinders

[mrmaloof]

Asana: https://app.asana.com/0/0/task/1209792245907491

What changed

• AppLayout.jsx — For users with access_type === 'DATAKINDER', when shared Inertia institution includes a name, the sidebar shows that name under the logo as a link to set/switch institution (route('set-inst')).
• resources/css/app.css — Default <a> styles in @layer base: link color from theme('colors.link.DEFAULT'), hover from secondary, focus-visible outline from input.focus, color transition, and a rule so links whose only direct child is an <img> stay decoration-free (e.g. logo). Uses theme() instead of stacked @apply for these rules.

Why it changed

• When Datakinders set an institution per session; showing the current institution name clarifies tenant context.
• Central default link styling aligns new links with tokens in tailwind.config.js.
• block on the institution link fixes inline <a> ignoring margin-top.