fix(lint): reduce nesting depth to ≤4 (E010)
Extract helpers to reduce deep nesting in 7 functions:
- display_ai_commits: extract make_commit_row helper
- write_query: extract write_values helper
- of_identifier: extract parse_params_loop, extract_query_name,
make_derived_component, resolve_ident_with_params
- verify: move check_not_future/check_max_age_helper to module level,
flatten nested match with Option.fold
- decode (h2_hpack): remove begin/end, compound saw_first_header guard
- request (one.ml): extract make_h2_direct_response helper
- request_internal: extract make_h2_conn_response/make_h2_alpn_response