fix(headless-login): show parsed jwks n preview

- reproduce the missing n preview with the actual parsedKeys response shape
- read nPreview from DevFront instead of the old n field
- keep the preview text as provided by backend summaries

devfront/src/features/clients/ClientGeneralPage.tsx

@@ -102,12 +102,6 @@ function formatDateTime(value?: string) {
   return date.toLocaleString();
 }
 
-function previewKeyMaterial(value?: string) {
-  if (!value) return "-";
-  if (value.length <= 23) return value;
-  return `${value.slice(0, 10)}...${value.slice(-10)}`;
-}
-
 function ClientGeneralPage() {
   const params = useParams();
   const navigate = useNavigate();
@@ -1347,7 +1341,7 @@ function ClientGeneralPage() {
                                   )}
                                 </p>
                                 <p className="break-all rounded-lg border border-border bg-background px-3 py-2 font-mono text-[11px]">
-                                  {previewKeyMaterial(key.n)}
+                                  {key.nPreview || "-"}
                                 </p>
                               </div>
                             </div>

devfront/src/lib/devApi.ts

@@ -80,7 +80,7 @@ export type ClientDetailResponse = {
       kty?: string;
       use?: string;
       alg?: string;
-      n?: string;
+      nPreview?: string;
     }>;
   };
 };

devfront/tests/devfront-clients-lifecycle.spec.ts

@@ -149,7 +149,8 @@ test.describe("DevFront clients lifecycle", () => {
                 kty: "RSA",
                 use: "sig",
                 alg: "RS256",
-                n: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
+                nPreview:
+                  "voVbHlo_UHkj...Hb8PiTCQ",
               },
             ],
           },
@@ -229,7 +230,7 @@ test.describe("DevFront clients lifecycle", () => {
       await expect(page.getByText(algorithm, { exact: true }).last()).toBeVisible();
     }
     await expect(
-      page.getByText("abcdefghij...0123456789", { exact: true }),
+      page.getByText("voVbHlo_UHkj...Hb8PiTCQ", { exact: true }),
     ).toBeVisible();
     await expect(
       page.getByRole("button", { name: /refresh|새로고침/i }),

devfront/tests/helpers/devfront-fixtures.ts

@@ -33,7 +33,7 @@ export type Client = {
       kty?: string;
       use?: string;
       alg?: string;
-      n?: string;
+      nPreview?: string;
     }>;
   };
   metadata?: Record<string, unknown>;