feat: brand color system + Kanban view (admin + client)

- Fix button contrast: add all missing shadcn tokens (primary-foreground,
  ring, input, muted, destructive) aligned to iamcavalli brand
- NavBar: #1A463C green bar with white text
- Login page: clean brand layout with iamcavalli wordmark
- Admin pages: brand colors on headings, borders, links
- Admin ClientRow: semantic payment badges (green/yellow/red)
- Admin phases tab: Lista ↔ Kanban toggle with @dnd-kit drag & drop
  between Da fare / In corso / Fatto columns (optimistic updates)
- Client dashboard: Timeline ↔ Kanban toggle, expandable task cards
  with approve button + comment form inline

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/admin/NavBar.tsx

@@ -6,12 +6,12 @@ import { Button } from "@/components/ui/button";
 
 export function NavBar() {
   return (
-    <nav className="border-b border-gray-200 bg-white px-6 py-3 flex items-center justify-between">
+    <nav className="bg-[#1A463C] px-6 py-3 flex items-center justify-between">
       <div className="flex items-center gap-6">
-        <span className="font-semibold text-gray-900">ClientHub</span>
+        <span className="font-bold text-white tracking-tight">iamcavalli</span>
         <Link
           href="/admin"
-          className="text-sm text-gray-600 hover:text-gray-900 transition-colors"
+          className="text-sm text-white/70 hover:text-white transition-colors"
         >
           Clienti
         </Link>
@@ -20,7 +20,7 @@ export function NavBar() {
         variant="ghost"
         size="sm"
         onClick={() => signOut({ callbackUrl: "/admin/login" })}
-        className="text-sm text-gray-500"
+        className="text-sm text-white/70 hover:text-white hover:bg-white/10"
       >
         Esci
       </Button>