fix(ocaml-uslp): pass all merlint checks
- Fix Fmt.invalid_arg, make_frame→frame, find_clcw→clcw in uslp.ml
- Extract decode_fecf helper to reduce function length
- Update uslp.mli with renamed functions and fixed docs
- Restructure test suite to single tuple; fix Fmt/Printf usage
- Add test_uslp.mli and update test.ml entry point
- Fix gen_corpus.ml to use print_endline (no fmt dep)
- Add fuzz_uslp.mli with module/suite docs
- Fix fuzz suite name "crowbar"→"uslp" (E725)
- Add fuzz.ml runner and update dune (E718)