cid-5019: Migrate to Spring Boot 4 and Kotlin 2.3.0

[henriq-amaral-leanix]

🛠 Changes made

• Add version 2.4.0 to resilience4j-spring-boot4 dependency
• Add spring-boot-webmvc-test for @WebMvcTest (moved module in SB4)
• Replace UnusedPrivateMember detekt rule with its three successors
• Update Jackson module kotlin imports to tools.jackson.module.kotlin
• Rename GITHUB_AGENT_VERSION to githubAgentVersion (lateinit var naming)
• Rename pemPrefix/pemSuffix to PEM_PREFIX/PEM_SUFFIX (const val naming)
• Remove com.fasterxml ObjectMapper injection from WebSocketClientConfig (SB4 no longer registers a com.fasterxml ObjectMapper bean)
• Update @WebMvcTest import to new package in test

✨ Type of change

Please delete the options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

🧪 How Has This Been Tested?

• Local tests
• Tests already implemented

🏎 Checklist:

• My code follows the style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md)
• My commit message clearly reflects the changes made
• Assigned the appropriate labels (version, PR type, etc.)

[internal-ai-adoption-analytics]

📊 Survey: Please help us track internal AI adoption. This is not for evaluation, only for metrics. You can update this anytime before merge.
🤖 Which AI developer tool(s), if any, were used to assist with this PR? Please tick one or more boxes below:

• None
• Cline
• Claude Code
• Cursor
• GitHub Copilot
• Other

🧑‍💻 If AI was used, what was it mainly used for?

• Coding / Implementation
• Testing (unit, integration, e2e)
• Documentation
• Research / Investigation
• Refactoring / Cleanup
• Configuration / DevOps
• Other

Thank you in advance for your feedback.💙🙏🎉
Here's a joke to brighten your day: What's the difference between AI and a toddler? The toddler eventually stops asking 'why?'! 👶

[github-actions]

LeanIX GitHub Agent Code Coverage

Overall Project	64.09% -4.03%	🍏
Files changed	74.7%	🍏

File	Coverage
GenericWebhookEvent.kt	100%	🍏
RepositoryRequestDTO.kt	100%	🍏
RateLimitType.kt	100%	🍏
GitHubAppResponse.kt	100%	🍏
PushEventPayload.kt	100%	🍏
GitHubAgentProperties.kt	100%	🍏
GitHubEnterpriseProperties.kt	100%	🍏
FeignClientConfig.kt	100%	🍏
ApplicationReadyListener.kt	100%	🍏
AgentConnectionScheduler.kt	100%	🍏
WebhookEventService.kt	100%	🍏
GitHubStartService.kt	100%	🍏
LeanIXAuthService.kt	100%	🍏
GitHubWebhookController.kt	100%	🍏
GitHubWebhookService.kt	98.33%	🍏
GitHubAPIService.kt	97.67%	🍏
GitHubScanningService.kt	93.6%	🍏
GitHubEnterpriseService.kt	91.11%	🍏
LeanIXProperties.kt	90% -10%	🍏
ConfigurationSetHandler.kt	87.63% -3.09%	❌
RepositoryGetHandler.kt	87.5% -3.41%	❌
SyncLogDto.kt	87.5% -2.5%	🍏
ArtifactDownloadHandler.kt	84.04% -0.98%	🍏
WebSocketClientConfig.kt	83.63%	🍏
GradlePropertiesConfiguration.kt	82.22% -6.67%	🍏
InstallationRequestDTO.kt	80% -20%	🍏
ArtifactsDto.kt	78.57%	🍏
ManifestFileUpdateDto.kt	76.92% -5.77%	🍏
ManifestFilesDTO.kt	75% -8.33%	🍏
GitHubAuthenticationService.kt	74.73% -4.54%	🍏
GitHubSearchResponse.kt	73.68% -10.53%	🍏
SyncLogService.kt	72.55% -0.65%	🍏
OrganizationDto.kt	71.43% -28.57%	🍏
CachingService.kt	66.35% -25.96%	❌
PagedRepositories.kt	65.63% -6.25%	🍏
JwtDto.kt	63.64%	🍏
GitHubResponsesDto.kt	59.46% -8.11%	🍏
GitHubClient.kt	58.33%	🍏
AgentSetupValidation.kt	57.78%	🍏
ArtifactDTO.kt	57.14% -42.86%	❌
InstallationGetHandler.kt	41.5% -3.5%	❌
Resilience4jConfig.kt	39.84% -13.82%	❌
GlobalExceptionHandler.kt	36.26%	🍏
Exceptions.kt	33.9% -11.86%	❌
GitHubAgentApplication.kt	28.89% -2.22%	🍏
FullScanHandler.kt	21.62% -4.05%	❌
RateLimitHandler.kt	20.69% -6.9%	🍏
BrokerStompSessionHandler.kt	20.16% -2.42%	❌
FullScanService.kt	13.04%	🍏
GitHubRepositoryService.kt	9.79% -6.19%	❌
RateLimitResponseInterceptor.kt	3.33%	🍏
GitHubGraphQLService.kt	1.82% -9.84%	❌
RateLimitHelper.kt	0% -95.83%	❌
RateLimitMonitor.kt	0% -1.54%	❌
RateLimitInterceptor.kt	0% -19.74%	❌