Add Java 21 to 25 baseline review rule

[JuanTorchia]

Summary

• Add java-21-to-25-baseline-review as the first implemented Java 21 -> 25 catalog rule.
• Keep the finding BASELINE / INFO and evidence-backed from declared Java version plus target version.
• Add positive and negative analyzer tests.
• Document the implementation in the engineering log.

Closes #8

Verification

• mvn -pl analyzer-core test -> 17 tests passed
• mvn test -> 34 tests passed