Update the credits section to make reference and amount optional

Modify the client-side schema and UI for the "Avoirs" page to make "invoiceReference" and "amount" fields optional, and reposition the "Avoirs" link in the sidebar.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 9fcf4b21-eb0c-4e53-a567-e2ce4a6ad869
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/9fcf4b21-eb0c-4e53-a567-e2ce4a6ad869/0C3uBiZ

client/src/components/Sidebar.tsx

@@ -255,6 +255,12 @@ export default function Sidebar() {
       icon: FileText, 
       roles: ["admin", "directeur"] 
     },
+    { 
+      path: "/avoirs", 
+      label: "Avoirs", 
+      icon: Receipt, 
+      roles: ["admin", "directeur", "manager"] 
+    },
     { 
       path: "/publicities", 
       label: "Publicités", 
@@ -285,12 +291,6 @@ export default function Sidebar() {
       icon: Wrench, 
       roles: ["admin", "directeur", "manager", "employee"] 
     },
-    { 
-      path: "/avoirs", 
-      label: "Avoirs", 
-      icon: Receipt, 
-      roles: ["admin", "directeur", "manager"] 
-    },
   ];
 
   const adminItems = [