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/app/(auth)/login/page.tsx

@@ -2,11 +2,10 @@
 
 import { useState } from "react";
 import { useRouter } from "next/navigation";
-import Link from "next/link";
 import { useAuth } from "@/lib/auth";
 
 export default function LoginPage() {
-  const [email, setEmail] = useState("");
+  const [rut, setRut] = useState("");
   const [password, setPassword] = useState("");
   const [error, setError] = useState("");
   const [loading, setLoading] = useState(false);
@@ -18,7 +17,7 @@ export default function LoginPage() {
     setError("");
     setLoading(true);
     try {
-      await login(email, password);
+      await login(rut, password);
       router.push("/");
     } catch (err: any) {
       setError(err.message || "Credenciales inválidas");
@@ -75,13 +74,13 @@ export default function LoginPage() {
 
           <form onSubmit={handleSubmit}>
             <div className="mb-3">
-              <label className="form-label">Correo Electrónico</label>
+              <label className="form-label">RUT</label>
               <input
-                type="email"
+                type="text"
                 className="form-control"
-                placeholder="tu@email.com"
-                value={email}
-                onChange={(e) => setEmail(e.target.value)}
+                placeholder="12.345.678-9"
+                value={rut}
+                onChange={(e) => setRut(e.target.value)}
                 required
                 autoFocus
               />
@@ -117,15 +116,6 @@ export default function LoginPage() {
               )}
             </button>
           </form>
-
-          <div className="text-center mt-4">
-            <span className="text-muted" style={{ fontSize: "0.9rem" }}>
-              ¿No tienes cuenta?{" "}
-              <Link href="/register" style={{ color: "var(--primary)", fontWeight: 500 }}>
-                Regístrate aquí
-              </Link>
-            </span>
-          </div>
         </div>
       </div>
     </div>