fix(fuzz): restructure tls-eio fuzz tests to pass E700/E718/E722 lint rules
- Replace (test ...) stanza with (executable ...) + explicit runtest/fuzz
alias rules (E722)
- Add gen_corpus.ml for AFL seed corpus generation (E718)
- Extract all test logic into fuzz_tls.ml exposing a suite value;
fuzz.ml now delegates via Fuzz_tls.suite (E700)
- Fix crowbar: run suites immediately instead of at_exit, enabling
direct suite delegation without global mutable state