Fix backend security, validation, and API contracts

src/main/resources/application.yml

@@ -20,7 +20,7 @@ spring:
 
   jpa:
     hibernate:
-      ddl-auto: none
+      ddl-auto: validate
       naming:
         physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
     show-sql: ${JPA_SHOW_SQL:false}
@@ -29,6 +29,11 @@ spring:
         format_sql: true
         dialect: org.hibernate.dialect.MySQLDialect
 
+  flyway:
+    enabled: true
+    baseline-on-migrate: true
+    baseline-version: 0
+
 server:
   port: ${SERVER_PORT:8080}
   servlet: