feat(10-02): implement lead management UI with list, detail, and form pages

- Create /admin/leads list page with LeadTable component showing all leads
- Implement /admin/leads/[id] detail page with activity log and reminders
- Add LeadForm component (CreateLeadModal and EditLeadModal) for CRUD operations
- Create server actions (createLead, updateLead, deleteLead) with Zod validation
- Add missing UI components (dialog.tsx, form.tsx) from shadcn
- Install date-fns for date formatting with Italian locale support
- All routes compile successfully with npm run build

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

package.json

@@ -13,14 +13,16 @@
     "@dnd-kit/sortable": "^10.0.0",
     "@dnd-kit/utilities": "^3.2.2",
     "@hookform/resolvers": "^5.2.2",
+    "@radix-ui/react-dialog": "^1.1.16",
     "@radix-ui/react-label": "^2.1.8",
     "@radix-ui/react-progress": "^1.1.8",
     "@radix-ui/react-select": "^2.2.6",
     "@radix-ui/react-separator": "^1.1.8",
-    "@radix-ui/react-slot": "^1.2.4",
+    "@radix-ui/react-slot": "^1.2.5",
     "@radix-ui/react-tabs": "^1.1.13",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "date-fns": "^4.4.0",
     "drizzle-orm": "^0.45.2",
     "lucide-react": "^1.14.0",
     "nanoid": "^5.1.11",