feat(check): java public-class ⇄ file-name mismatch — layout finding with a ready jmove mv repair

- parser::java::class_name: exactly-one-public-top-level-type rule
  (package-info/module-info and 0-or-2-public files skipped)
- check gains name_mismatches[] (JSON, omitted when clean) + human lines;
  exit 2 covers both kinds; fix engine untouched by design — a file rename
  is not a byte edit, and mv keeps the FQN so no imports change
- output split into output/{mod,check} to stay under the 250-line rule
- e2e: reports Bad.java, stays quiet on Good.java, suggested rename makes
  check pass and preserves the file bytes

tests/cli.rs

@@ -105,7 +105,7 @@ fn check_passes_on_clean_and_fails_on_broken_fixture() {
     let clean = fixture("basic");
     jmove(&clean, &["check"])
         .success()
-        .stdout(predicate::str::contains("no broken imports"));
+        .stdout(predicate::str::contains("check: no findings"));
 
     let messy = fixture("complex");
     jmove(&messy, &["check"])