feat: add SensitiveKeysConfig record and SensitiveKeysRepository interface

cameleer3-server-core/src/main/java/com/cameleer3/server/core/admin/SensitiveKeysConfig.java

@@ -0,0 +1,10 @@
+package com.cameleer3.server.core.admin;
+
+import java.util.List;
+
+public record SensitiveKeysConfig(List<String> keys) {
+
+    public SensitiveKeysConfig {
+        keys = keys != null ? List.copyOf(keys) : List.of();
+    }
+}

cameleer3-server-core/src/main/java/com/cameleer3/server/core/admin/SensitiveKeysRepository.java

@@ -0,0 +1,8 @@
+package com.cameleer3.server.core.admin;
+
+import java.util.Optional;
+
+public interface SensitiveKeysRepository {
+    Optional<SensitiveKeysConfig> find();
+    void save(SensitiveKeysConfig config, String updatedBy);
+}