[Studio] feat: add core common foundation module with unified response, base entity, enums and global exception handling

[zhaohai666]

PR Title

[studio] feat: add core common foundation module with unified response, base entity, enums and global exception handling

Overview

This module serves as the foundational common component of the project, delivering standardized response wrappers (Result / PageResult), base entity BaseEntity, 16 business enumerations, global exception handling logic (BusinessException + GlobalExceptionHandler), CORS cross-origin setup and web interceptor configuration. All page-related PRs depend on this module.

Source Code Files (10 files total)

• StudioApplication.java — Spring Boot application entry point
• common/config/CorsConfig.java — CORS cross-origin configuration allowing all origins
• common/config/WebConfig.java — Web interceptor configuration
• common/domain/BaseEntity.java — Base entity with id, createdAt and updatedAt fields
• common/domain/PageResult.java — Pagination response wrapper with static factory methods of() and empty()
• common/domain/Result.java — Unified HTTP response wrapper with static factory methods ok() and error()
• common/domain/enums/*.java — 16 business enums:
  ClusterStatus, BrokerRole, ClientType, ConsumerStatus, MessageType, AlertLevel, AlertStatus, AlertMetric, AuditOperation, AuditResult, DataSourceType, InstanceStatus, NameServerStatus, ProxyStatus, TopicStatus, QueueType
• common/exception/BusinessException.java — Custom business runtime exception carrying error code and message
• common/exception/GlobalExceptionHandler.java — Global exception handler annotated with @RestControllerAdvice

Test Coverage

8 test files with total 632 lines of test code:

Test File	Lines	Test Methods	Coverage Scope
ResultTest.java	80	6	ok() with data/empty/null payload; error() with various error codes; complex object serialization
PageResultTest.java	72	5	Build page via of(), empty page via empty(), pagination parameter validation, edge cases
BaseEntityTest.java	70	5	Field assignment for id/createdAt/updatedAt, default values, equals() & hashCode()
EnumsTest.java	190	16 @nested	Each nested class verifies values() and valueOf() for one business enum
BusinessExceptionTest	57	4	Multi-parameter constructors, RuntimeException inheritance, getCode() & getMessage()
GlobalExceptionHandlerTest	71	3	Capture business exceptions and return standardized error Result; capture unknown exceptions and return 500 error
CorsConfigTest.java	48	3	Validate @Configuration annotation, existence of CorsFilter bean, wildcard origin access policy
WebConfigTest.java	44	3	Validate @Configuration annotation and implementation of WebMvcConfigurer

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All PR and Issue titles associated with this project must start with the [studio] prefix.
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