[codex] Add Vlad course based code review

[jojoldu]

Summary

• Adds a Markdown code-review report based on high-performance Hibernate/JPA review criteria inspired by Vlad Mihalcea's course material.
• Focuses on Querydsl paging readers, no-offset keyset pagination, transaction behavior, fetch strategy, restart behavior, and projection safety.
• Does not change production code.

Verification

• ./gradlew test was attempted.
• Default JDK 25 failed with Unsupported class file major version 69 under Gradle 6.7.1.
• JDK 11 got past that point but failed during build configuration because org.ajoberstar.grgit:grgit-core:3.1.1 could not be resolved from the plugin repository.