Add missing periods to doc comments, fix [name] format mismatches,
rename camelCase variant constructors to snake_case in hooks.ml,
and apply dune fmt formatting.

Flatten multi-group test suites to single pairs (string * test_case list)
across bpsec, btree, bundle, bytesrw-eio, cfdp, cgr, claude-skills, and
claudeio. Update test.ml runners to wrap suites in lists. Add missing
test_cache.mli. Fix E600 linter to skip standalone executables and
utility libraries that happen to have a test_ prefix by checking whether
the corresponding .ml defines a suite value.

Fix E617 by renaming test suite names to match filenames (remove 'u'
prefix in btree/cbort, lowercase in cgr). Fix E605 by extracting
cache tests into test_cache.ml and adding test_outgoing.ml stub.
Improve e605 rule to generically handle any source directory instead
of hardcoding lib/src/proto — non-standard dirs are preserved under
test/ (e.g. proto/foo.ml -> test/proto/test_foo.ml).