docs: add IDEA shadow deployment and rollback guide

ruoyi-admin/src/main/resources/application.yml

@@ -178,3 +178,15 @@ xss:
 mybatis-plus:
   configuration:
     log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
+
+# 影子算法默认关闭；现场测试仅通过 IDEA 环境变量显式开启
+fortucky:
+  shadow:
+    enabled: ${FORTUCKY_SHADOW_ENABLED:false}
+    warehouse-id: ${FORTUCKY_SHADOW_WAREHOUSE_ID:}
+    timeout-seconds: ${FORTUCKY_SHADOW_TIMEOUT_SECONDS:3}
+  algorithm:
+    mode: ${FORTUCKY_ALGORITHM_MODE:SHADOW}
+    warehouse-id: ${FORTUCKY_ALGORITHM_WAREHOUSE_ID:01}
+    database-writes-enabled: ${FORTUCKY_ALGORITHM_DATABASE_WRITES_ENABLED:true}
+    legacy-fallback-on-technical-error: ${FORTUCKY_ALGORITHM_LEGACY_FALLBACK_ON_TECHNICAL_ERROR:false}