feat: restrict gamme/export/exports-page to admin; fix create user button style

- Non-admin users see gamme as read-only badge (no select)
- Export button hidden for non-admin in grid
- Save drafts button hidden for non-admin
- Exports page hidden in sidebar for non-admin
- Create user button: explicit blue style (was unreadable with apple-btn-primary)

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

src/components/shared/sidebar.tsx

@@ -14,7 +14,7 @@ const NAV_ITEMS = [
     { icon: TrendingUp, label: "Analytics", href: "/analytics" },
     { icon: Trophy, label: "Hit Parade", href: "/hit-parade" },
     { icon: Camera, label: "Snapshots", href: "/snapshots" },
-    { icon: FileDown, label: "Exports", href: "/exports" },
+    { icon: FileDown, label: "Exports", href: "/exports", adminOnly: true },
     { icon: Settings, label: "Paramètres", href: "/settings", adminOnly: true },
 ];