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/dashboard/date-range-picker.tsx

@@ -149,7 +149,7 @@ export function DateRangePicker({ value, onChange, className }: DateRangePickerP
                    empty result, and not understand why. */
                 max={draftTo && draftTo < today ? draftTo : today}
                 onChange={(e) => setDraftFrom(e.target.value)}
-                className="w-auto max-w-full rounded-md border border-input bg-background px-2 py-1.5 text-sm outline-none focus:border-brand/60 focus:ring-2 focus:ring-brand/15"
+                className="w-auto max-w-full rounded-md border border-input bg-background px-2 py-1.5 text-sm outline-hidden focus:border-brand/60 focus:ring-2 focus:ring-brand/15"
               />
             </label>
             <label className="block text-xs">
@@ -160,7 +160,7 @@ export function DateRangePicker({ value, onChange, className }: DateRangePickerP
                 min={draftFrom || undefined}
                 max={today}
                 onChange={(e) => setDraftTo(e.target.value)}
-                className="w-auto max-w-full rounded-md border border-input bg-background px-2 py-1.5 text-sm outline-none focus:border-brand/60 focus:ring-2 focus:ring-brand/15"
+                className="w-auto max-w-full rounded-md border border-input bg-background px-2 py-1.5 text-sm outline-hidden focus:border-brand/60 focus:ring-2 focus:ring-brand/15"
               />
             </label>
             <div className="flex items-center justify-end gap-2 pt-1">