Set up CodeRabbit AI and CODEOWNERS file

[rammrain]

Summary

Configure CodeRabbit AI for automated PR reviews and add a CODEOWNERS file to enforce review requirements across the repository.

CodeRabbit AI

• Install the CodeRabbit GitHub App on the repository
• Add .coderabbit.yaml configuration file with project-specific review settings
• Configure review language, tone, and scope appropriate for a Java SDK
• Enable auto-summary on PRs
• Verify CodeRabbit posts review comments on a test PR

CODEOWNERS

• Create .github/CODEOWNERS file
• Define ownership rules for key areas:
  • /src/main/ — core SDK maintainers
  • /src/test/ — core SDK maintainers
  • build.gradle, *.gradle — build/infra owners
  • .github/ — CI/DevOps owners
  • CLAUDE.md — AI tooling owners
• Enable branch protection rule requiring CODEOWNERS approval on main

Acceptance Criteria

• CodeRabbit automatically reviews incoming PRs with useful, context-aware feedback
• CODEOWNERS file is in place and GitHub enforces required reviews from designated owners
• Both configurations are documented