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>

package.json

@@ -9,6 +9,9 @@
     "lint": "eslint"
   },
   "dependencies": {
+    "@dnd-kit/core": "^6.3.1",
+    "@dnd-kit/sortable": "^10.0.0",
+    "@dnd-kit/utilities": "^3.2.2",
     "@hookform/resolvers": "^5.2.2",
     "@radix-ui/react-label": "^2.1.8",
     "@radix-ui/react-progress": "^1.1.8",