feat(deps): Tailwind 3 → 4 + swap tailwindcss-animate for tw-animate-css

Ran the official @tailwindcss/upgrade tool:
- tailwind.config.ts → @theme directive in globals.css
- @tailwind base/components/utilities → @import 'tailwindcss'
- postcss.config switched from tailwindcss + autoprefixer to
  @tailwindcss/postcss (autoprefixer baked in)
- focus-visible:outline-none → focus-visible:outline-hidden (the v3
  utility was a footgun — outline still showed in forced-colors mode)

Reverted the migration tool's over-zealous variant="outline" →
variant="outline-solid" rename on CVA prop values; that rename was
meant for the Tailwind `outline:` utility, not our Button/Badge
component variants.

Swapped tailwindcss-animate (v3-style JS plugin) for tw-animate-css
(v4-native @import). Same utility surface (animate-spin, animate-in,
etc.), one fewer JS plugin in the bundle.

Fixed the upgrade tool's malformed dark variant
(@custom-variant dark (&:is(class *)) — `class` was being parsed as
a tag) to canonical &:where(.dark, .dark *).

Verified: tsc 0 errors, eslint 0 errors (16 pre-existing warnings),
vitest 1315/1315, next build clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/admin/document-templates/template-form.tsx

@@ -165,7 +165,7 @@ export function TemplateForm({ open, onOpenChange, template, onSuccess }: Templa
                 validateJson(e.target.value);
               }}
               rows={18}
-              className="w-full rounded-md border border-input bg-background px-3 py-2 font-mono text-xs shadow-sm focus:outline-none focus:ring-2 focus:ring-ring"
+              className="w-full rounded-md border border-input bg-background px-3 py-2 font-mono text-xs shadow-sm focus:outline-hidden focus:ring-2 focus:ring-ring"
               spellCheck={false}
             />
             {jsonError && <p className="text-xs text-destructive">{jsonError}</p>}

src/components/admin/service-health-card.tsx

@@ -34,7 +34,7 @@ export function ServiceHealthCard({ service }: ServiceHealthCardProps) {
       <CardContent className="p-4">
         <div className="flex items-center gap-2 mb-2">
           <span
-            className={cn('h-2.5 w-2.5 rounded-full flex-shrink-0', config.dot)}
+            className={cn('h-2.5 w-2.5 rounded-full shrink-0', config.dot)}
             aria-hidden="true"
           />
           <span className="font-medium text-sm truncate">{service.name}</span>