feat(kanban): DnD + PATCH – flytta tasks mellan kolumner med optimistisk uppdatering

package.json

@@ -13,6 +13,9 @@
     "test:run": "vitest --run"
   },
   "dependencies": {
+    "@dnd-kit/accessibility": "^3.1.1",
+    "@dnd-kit/core": "^6.3.1",
+    "@dnd-kit/sortable": "^10.0.0",
     "@hookform/resolvers": "^5.2.2",
     "@tanstack/react-query": "^5.90.2",
     "class-variance-authority": "^0.7.1",
@@ -24,6 +27,7 @@
     "react-dom": "^19.1.1",
     "react-hook-form": "^7.64.0",
     "react-router-dom": "^7.9.4",
+    "sonner": "^2.0.7",
     "tailwind-merge": "^3.3.1",
     "zod": "^4.1.12",
     "zustand": "^5.0.8"