Upgrade Spring Boot from 2.2.0.M6 to 2.7.18

[callummiles]

Upgrade Spring Boot from 2.2.0.M6 to 2.7.18

Summary

This PR upgrades the project from Spring Boot 2.2.0.M6 (milestone/pre-release) to 2.7.18 (stable release), as a prerequisite for eventually upgrading to Java 17. All automated tests pass (181 unit tests + 22 integration tests).

Key Changes:

• Updated Spring Boot parent version to 2.7.18
• Removed snapshot/milestone repositories (no longer needed for stable releases)
• Updated all dependencies to compatible versions (Lombok, H2, Vavr, Spock, Groovy)
• Updated Maven plugins (Surefire, Failsafe, GMaven Plus)
• Added H2 MODE=LEGACY for backward compatibility with H2 1.x SQL syntax
• Updated Spring HATEOAS API usage to use static factory methods instead of constructors

Review & Testing Checklist for Human

This is a major framework upgrade. While all automated tests pass, manual verification is recommended:

• Start application locally: Run mvn spring-boot:run -Dspring-boot.run.profiles=dev and verify it starts without errors
• Test REST endpoints: Manually test a few REST API endpoints (e.g., /profiles/{patronId}/holds/) to ensure HATEOAS links are generated correctly
• Check for deprecation warnings: Review application logs for any deprecation warnings from Spring Boot 2.7.x
• Verify database operations: Test that database reads/writes work correctly with H2 2.x in LEGACY mode
• Long-term H2 strategy: Consider whether MODE=LEGACY is acceptable long-term, or if SQL scripts should be migrated to native H2 2.x syntax (this PR uses MODE=LEGACY as a compatibility workaround)

Test Plan

1. Start the application with the dev profile
2. Access health endpoint: http://localhost:8080/actuator/health
3. Test a few REST endpoints to verify HATEOAS functionality
4. Check H2 console if needed: http://localhost:8080/h2-console

Notes

Spring HATEOAS API Changes: Updated PatronProfileController to use CollectionModel.of() and EntityModel.of() instead of constructors (4 locations updated). These were the only occurrences found, but please verify.

H2 Database Compatibility: Used MODE=LEGACY in database URLs to maintain compatibility with H2 1.x SQL syntax. The SQL scripts use older syntax like INTEGER IDENTITY which would otherwise fail in H2 2.x. A future improvement would be migrating these scripts to H2 2.x native syntax.

Test Results: All tests pass locally:

• 181 unit tests: 0 failures
• 22 integration tests: 0 failures
• Build time: ~25 seconds

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Link to Devin run: https://app.devin.ai/sessions/3b7e3bb90cfd43b48642a7299f2e7966
Requested by: @callummiles

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