chore: accumulated lint fixes, test stubs, and interface files

- Fix E325 to skip type variables when checking get/find naming
- Add test.ml runners for bpsec, bytesrw-eio, cfdp, claude-skills
- Add .mli files for btree lib modules and test modules
- Add .mli files for cbort, cgr, bundle, bpsec, bytesrw-eio
- Add claudeio test module stubs and .mli files
- Add claudeio test/proto/dune for outgoing tests
- Fix claudeio examples Test_json_utils -> Json_utils references
- Add linkedin URL parsing module and tests
- Improve linkedin profile scraping and cookie handling
- Fix claude-skills main.ml lint issues
- Fix various .mli doc comment formatting