feat(contacts): add contacts page with per-store management and supplier email field

- New contacts table (group_id, name, role, phone, email, notes) per store
- Suppliers table: add email field with form and card display
- Page /contacts: two-column layout (suppliers read-only / free contacts CRUD)
- Permissions: read all roles, create/edit/delete admin + directeur + manager
- Admin can filter contacts by store; other roles see their own stores only
- Migration SQL: 20260515_add_contacts_and_supplier_email.sql

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

client/src/components/Sidebar.tsx

@@ -36,7 +36,8 @@ import {
   Send,
   Receipt,
   TrendingUp,
-  CreditCard
+  CreditCard,
+  BookUser,
 } from "lucide-react";
 
 export default function Sidebar() {
@@ -331,6 +332,12 @@ export default function Sidebar() {
           icon: Wrench,
           roles: ["admin", "directeur", "manager", "employee"]
         },
+        {
+          path: "/contacts",
+          label: "Contacts",
+          icon: BookUser,
+          roles: ["admin", "directeur", "manager", "employee"]
+        },
       ]
     },
   ];