feat: add PostgreSQL web installation wizard

oa-backend/src/main/java/com/kaidi/oa/seed/DemoSeed.java

@@ -0,0 +1,18 @@
+package com.kaidi.oa.seed;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.stereotype.Component;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Component
+@ConditionalOnProperty(name = "oa.seed.demo", havingValue = "true", matchIfMissing = true)
+public @interface DemoSeed {
+}