Upgrade to Spring Boot 4 #1545
Description
Action items and breaking changes for Spring Boot 4:
- Migrate to Spring Boot 4
- Resolve Use OpenAPI 3.1 fields #1487
- Resolve UI publish endpoint fails when spring.jackson.property-naming-strategy=SNAKE_CASE (payload fields generated in camelCase) #1535
- Address maintainer notes in source code comments
- Rename branch master to main