Migrate Spring Boot System Prompts to Skills

[jabrena]

https://github.com/jabrena/cursor-rules-spring-boot

• 301-frameworks-spring-boot-core.mdc -> OK
• 302-frameworks-spring-boot-rest.mdc -> OK
• 303-frameworks-spring-data-jdbc.mdc -> OK
• 304-frameworks-spring-boot-hikari.mdc -> NA
• 311-frameworks-spring-boot-slice-testing.mdc -> OK
• 312-frameworks-spring-boot-integration-testing.mdc -> OK
• 313-frameworks-spring-boot-local-testing.mdc -> OK
• 321-frameworks-spring-boot-native-compilation.mdc -> NA
• 500-sql.mdc -> OK