feat(web): gate settings nav by workspace role (MS21-RBAC-001) (#579)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/web/src/app/(authenticated)/settings/page.tsx

@@ -1,7 +1,10 @@
 "use client";
 
-import { useState } from "react";
+import { useCallback, useEffect, useState } from "react";
 import type { ReactElement, ReactNode } from "react";
+import { WorkspaceMemberRole } from "@mosaic/shared";
+import { useAuth } from "@/lib/auth/auth-context";
+import { fetchUserWorkspaces } from "@/lib/api/workspaces";
 import Link from "next/link";
 
 interface CategoryConfig {
@@ -11,6 +14,7 @@ interface CategoryConfig {
   accent: string;
   iconBg: string;
   icon: ReactNode;
+  adminOnly?: boolean;
 }
 
 interface SettingsCategoryCardProps {
@@ -200,6 +204,7 @@ const categories: CategoryConfig[] = [
     title: "Users",
     description: "Invite, manage roles, and deactivate users across your workspaces.",
     href: "/settings/users",
+    adminOnly: true,
     accent: "var(--ms-green-400)",
     iconBg: "rgba(34, 197, 94, 0.12)",
     icon: (
@@ -277,7 +282,30 @@ const categories: CategoryConfig[] = [
   },
 ];
 
+const ADMIN_ROLES: WorkspaceMemberRole[] = [WorkspaceMemberRole.OWNER, WorkspaceMemberRole.ADMIN];
+
 export default function SettingsPage(): ReactElement {
+  const { user } = useAuth();
+  const [isAdmin, setIsAdmin] = useState<boolean>(false);
+
+  const checkRole = useCallback(async (): Promise<void> => {
+    if (user === null) return;
+    try {
+      const workspaces = await fetchUserWorkspaces();
+      const hasAdminRole = workspaces.some((ws) => ADMIN_ROLES.includes(ws.role));
+      setIsAdmin(hasAdminRole);
+    } catch {
+      // Fail open — show all items if we can't determine role
+      setIsAdmin(true);
+    }
+  }, [user]);
+
+  useEffect(() => {
+    void checkRole();
+  }, [checkRole]);
+
+  const visibleCategories = categories.filter((c) => c.adminOnly !== true || isAdmin);
+
   return (
     <div className="max-w-6xl mx-auto p-6">
       {/* Page header */}
@@ -305,7 +333,7 @@ export default function SettingsPage(): ReactElement {
 
       {/* Category grid */}
       <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
-        {categories.map((category) => (
+        {visibleCategories.map((category) => (
           <SettingsCategoryCard key={category.href} category={category} />
         ))}
       </div>