refactor(admin-book): rename Result to ApiResult and tighten return types

- Replace `Result` with `ApiResult` across admin book/borrow modules
- Change return type from `Result<Any?>` to `ApiResult<String>`
- Reformat multi-arg log statements for readability

build.gradle.kts

@@ -27,6 +27,7 @@ dependencies {
     implementation("org.springframework.boot:spring-boot-starter-web")
     implementation("org.aspectj:aspectjweaver")
     implementation("org.springframework.security:spring-security-crypto")
+    implementation("org.springdoc:springdoc-openapi-starter-webmvc-ui:3.0.3")
     implementation("org.bouncycastle:bcprov-jdk18on:1.84")
     implementation("com.mysql:mysql-connector-j")
     implementation("com.baomidou:mybatis-plus-spring-boot4-starter:3.5.15")