upgrade checkstyle from a naming-only ruleset to a public-api gate:
- unusedimports: dead imports fail the build (zero violations existed
at adoption)
- missingjavadoctype/method: public types and members must carry
javadoc (scope public, @override exempt) - about 140 doc comments
were added across records, filters, stores and gRPC servers
- method name format now rejects find/query/fetch prefixes, encoding
the repo crud verb law (select stays reserved for mybatis mappers
and is policed by review)
- suppressions: skip protobuf generated-sources, which only enter the
scan in full-reactor builds
- spotless: ratchet checks to origin/main so legacy formatting debt
stops blocking unrelated changes and CI formats only what changed
pnoker