fix(headless-login): show full parsed jwks key values

- return the full RSA n value in parsedKeys responses
- render parsed key fields with labels and multiline key material in DevFront
- lock the behavior with backend and Playwright regression tests

backend/internal/domain/headless_jwks_cache.go

@@ -3,11 +3,11 @@ package domain
 import "time"
 
 type HeadlessJWKSParsedKey struct {
-	Kid      string `json:"kid,omitempty"`
-	Kty      string `json:"kty,omitempty"`
-	Use      string `json:"use,omitempty"`
-	Alg      string `json:"alg,omitempty"`
-	NPreview string `json:"nPreview,omitempty"`
+	Kid string `json:"kid,omitempty"`
+	Kty string `json:"kty,omitempty"`
+	Use string `json:"use,omitempty"`
+	Alg string `json:"alg,omitempty"`
+	N   string `json:"n,omitempty"`
 }
 
 // HeadlessJWKSCacheState는 headless login용 JWKS 캐시 상태와 최근 동기화 결과를 나타냅니다.

backend/internal/handler/dev_handler_test.go

@@ -10,7 +10,6 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
-	"strings"
 	"testing"
 	"time"
 
@@ -108,14 +107,6 @@ func devTestJWKSFirstKeyString(t *testing.T, jwks map[string]any, field string)
 	return value
 }
 
-func devTestPreviewValue(value string) string {
-	value = strings.TrimSpace(value)
-	if len(value) <= 24 {
-		return value
-	}
-	return value[:12] + "..." + value[len(value)-12:]
-}
-
 // --- Tests ---
 
 func TestListClients_Success(t *testing.T) {
@@ -855,7 +846,7 @@ func TestRefreshHeadlessJWKSCache_ReturnsUpdatedCacheState(t *testing.T) {
 	privateKey, jwks := mustHeadlessRSAJWK(t)
 	_ = privateKey
 	jwksBody, _ := json.Marshal(jwks)
-	expectedNPreview := devTestPreviewValue(devTestJWKSFirstKeyString(t, jwks, "n"))
+	expectedN := devTestJWKSFirstKeyString(t, jwks, "n")
 	redisRepo := &devMockRedisRepo{data: map[string]string{}}
 	h := &DevHandler{
 		Hydra: &service.HydraAdminService{
@@ -908,7 +899,7 @@ func TestRefreshHeadlessJWKSCache_ReturnsUpdatedCacheState(t *testing.T) {
 			assert.Equal(t, "RSA", got.HeadlessJWKSCache.ParsedKeys[0].Kty)
 			assert.Equal(t, "sig", got.HeadlessJWKSCache.ParsedKeys[0].Use)
 			assert.Equal(t, "RS256", got.HeadlessJWKSCache.ParsedKeys[0].Alg)
-			assert.Equal(t, expectedNPreview, got.HeadlessJWKSCache.ParsedKeys[0].NPreview)
+			assert.Equal(t, expectedN, got.HeadlessJWKSCache.ParsedKeys[0].N)
 		}
 	}
 }

backend/internal/service/headless_jwks_cache.go

@@ -390,24 +390,16 @@ func summarizeHeadlessJWKS(raw string) []domain.HeadlessJWKSParsedKey {
 	parsedKeys := make([]domain.HeadlessJWKSParsedKey, 0, len(document.Keys))
 	for _, key := range document.Keys {
 		parsedKeys = append(parsedKeys, domain.HeadlessJWKSParsedKey{
-			Kid:      strings.TrimSpace(key.Kid),
-			Kty:      strings.TrimSpace(key.Kty),
-			Use:      strings.TrimSpace(key.Use),
-			Alg:      strings.TrimSpace(key.Alg),
-			NPreview: previewHeadlessJWKValue(key.N),
+			Kid: strings.TrimSpace(key.Kid),
+			Kty: strings.TrimSpace(key.Kty),
+			Use: strings.TrimSpace(key.Use),
+			Alg: strings.TrimSpace(key.Alg),
+			N:   strings.TrimSpace(key.N),
 		})
 	}
 	return parsedKeys
 }
 
-func previewHeadlessJWKValue(value string) string {
-	value = strings.TrimSpace(value)
-	if len(value) <= 24 {
-		return value
-	}
-	return value[:12] + "..." + value[len(value)-12:]
-}
-
 func extractHeadlessKids(keySet *jose.JSONWebKeySet) []string {
 	if keySet == nil {
 		return nil