Configure Spotless Maven plugin or remove CI formatting check

[dfcoffin]

PR Validation in .github/workflows/pr-checks.yml references mvn spotless:check, but no project pom configures the Spotless plugin. The step has been commented out with a TODO.

Decision needed:

• Option A: Add Spotless to the root POM with a chosen style (e.g., Google AOSP, Palantir). Run spotless:apply once to format the whole codebase, accept the large reformat commit, then re-enable the CI check.

• Option B: Remove the step permanently from pr-checks.yml and accept that the project doesn’t enforce automated formatting.