Adapt frontend to SAM API: RUT auth, new types, helpdesk endpoints

- Login: RUT-based (SAM auth) instead of email
- API client: updated all endpoints to /api/helpdesk/*
- Types: match SAM response format (nombre, apPaterno, perfil)
- Dashboard: uses new DashboardStats with dailyCounts
- Tickets: title instead of subject, requesterName/assigneeName
- KB: categoryName/authorName instead of nested objects
- Removed register page (SAM manages users)

frontend/src/components/Sidebar.tsx

@@ -12,10 +12,15 @@ export default function Sidebar() {
     { href: "/", icon: "bi-speedometer2", label: "Dashboard" },
     { href: "/tickets", icon: "bi-ticket-detailed", label: "Tickets" },
     { href: "/knowledge-base", icon: "bi-journal-bookmark", label: "Knowledge Base" },
-    { href: "/users", icon: "bi-people", label: "Users" },
-    { href: "/settings", icon: "bi-gear", label: "Settings" },
   ];
 
+  const initials = user?.nombre
+    ?.split(" ")
+    .map((n: string) => n[0])
+    .join("")
+    .toUpperCase()
+    .slice(0, 2) || "U";
+
   return (
     <aside className="sidebar" id="sidebar">
       <div className="sidebar-brand">
@@ -42,17 +47,10 @@ export default function Sidebar() {
       </nav>
 
       <div className="sidebar-user">
-        <div className="avatar">
-          {user?.name
-            ?.split(" ")
-            .map((n) => n[0])
-            .join("")
-            .toUpperCase()
-            .slice(0, 2) || "U"}
-        </div>
+        <div className="avatar">{initials}</div>
         <div className="sidebar-user-info">
-          <div className="name">{user?.name || "Usuario"}</div>
-          <div className="role">{user?.role || "Agente"}</div>
+          <div className="name">{user?.nombre || "Usuario"}</div>
+          <div className="role">{user?.perfil || "Agente"}</div>
         </div>
         <button
           onClick={logout}