鍵ファイルのドキュメント改善

- コメントに AN12436/AN12413 リファレンス追加
- プレースホルダー鍵値の説明を明確化
- 本番環境とテスト環境の使い分けを文書化

TODO: PDF から実際の鍵値を取得して置き換え
  - NXP AN12436: https://www.nxp.com/docs/en/application-note/AN12436.pdf
  - NXP AN12413: https://www.nxp.com/docs/en/application-note/AN12413.pdf

src/se050_scp03_keys.c

@@ -2,13 +2,18 @@
  * @file se050_scp03_keys.c
  * @brief SE050 Platform SCP03 Keys Implementation
  * 
- * Platform SCP03 keys for each SE050 chip type.
+ * Platform SCP03 keys for each SE050 chip type (SE050C0, SE050C1, SE050E2).
  * 
- * IMPORTANT: These are placeholder values. Replace with actual keys from:
- * - NXP documentation
- * - Secure provisioning process
+ * IMPORTANT: These are placeholder values for testing only.
+ * Replace with actual keys from:
+ * - NXP AN12436 application note (PlatformSCP03 default keys)
+ * - NXP AN12413 application note (SCP03 security configuration)
+ * - Secure provisioning process for production
  * - Your organization's key management system
  * 
+ * For production use: Each chip should have unique, securely provisioned keys.
+ * For testing: Use the default keys from AN12436 or your chip documentation.
+ * 
  * License: MIT (Clean-room implementation)
  */
 
@@ -17,8 +22,8 @@
 /* ============================================================================
  * SE050C0 Platform SCP03 Keys
  * 
- * TODO: Replace with actual keys from NXP documentation or secure provisioning
- * Reference: [Add PDF reference here]
+ * TODO: Replace with actual keys from AN12436 or secure provisioning
+ * Reference: NXP AN12436 "SE050 configurations" - Section on PlatformSCP03
  * ============================================================================ */
 
 const uint8_t SE050C0_ENC_KEY[16] = {
@@ -39,8 +44,8 @@ const uint8_t SE050C0_DEK_KEY[16] = {
 /* ============================================================================
  * SE050C1 Platform SCP03 Keys
  * 
- * TODO: Replace with actual keys from NXP documentation or secure provisioning
- * Reference: [Add PDF reference here]
+ * TODO: Replace with actual keys from AN12436 or secure provisioning
+ * Reference: NXP AN12436 "SE050 configurations" - Section on PlatformSCP03
  * ============================================================================ */
 
 const uint8_t SE050C1_ENC_KEY[16] = {
@@ -61,8 +66,8 @@ const uint8_t SE050C1_DEK_KEY[16] = {
 /* ============================================================================
  * SE050E2 Platform SCP03 Keys
  * 
- * TODO: Replace with actual keys from NXP documentation or secure provisioning
- * Reference: [Add PDF reference here]
+ * TODO: Replace with actual keys from AN12436 or secure provisioning
+ * Reference: NXP AN12436 "SE050 configurations" - Section on PlatformSCP03
  * ============================================================================ */
 
 const uint8_t SE050E2_ENC_KEY[16] = {