feat(auth): implement JWT authentication

- Add JwtUtils for token generation and validation using jjwt
- Refactor AuthService.login to return User instead of Boolean
- Add jjwt dependencies and integrate JWT into login flow
- Externalize JWT secret, expiration, and log level as configurable env vars with defaults

src/main/resources/application.yaml

@@ -9,8 +9,8 @@ spring:
   jackson:
     default-property-inclusion: non_null
     property-naming-strategy: SNAKE_CASE
-    date-format: ${JSON_DATE_FORMAT}
-    time-zone: ${JSON_TIME_ZONE}
+    date-format: ${JSON_DATE_FORMAT:}
+    time-zone: ${JSON_TIME_ZONE:}
 
 mybatis-plus:
   configuration:
@@ -18,6 +18,10 @@ mybatis-plus:
     map-underscore-to-camel-case: true
     # 开启日志输出sql语句
     # log-impl: org.apache.ibatis.logging.commons.JakartaCommonsLoggingImpl
-# logging:
-#   level:
-#     com.msksbr.bookmgr: "DEBUG"
+logging:
+  level:
+    com.msksbr.bookmgr: ${LOG_LEVEL:INFO}
+
+jwt:
+  secret: ${JWT_SECRET:}
+  expiration: ${JWT_EXPIRATION_TIME:86400000}