CH table metadata: omie.offer_headers

# `omie.offer_headers` Complex day-ahead offer HEADER (OMIE `cab` — Mercado Diario → 4. Ofertas → "Cabecera de las ofertas al mercado diario"). One row per offer per delivery day; carries the complex conditions (indivisibility, gradient, MIC linkage per the OMIE catalog description) that the plain curva_pbc/curva_pbc_uof blocks don't expose. Join to omie.offer_blocks on (datetime, program, offer_code) for the per-tramo detail. Fixed-width, undocumented file format — REVERSE-ENGINEERED from real files by comparing byte positions across 2653 real rows on 2026-01-01 (never-varying whitespace columns mark field boundaries), not from an official OMIE spec (none was found published anywhere public). Published ~90 days late, same lag shape as the continuous order book (orders/trades/pibcic) — the newest month in the catalog is always still accumulating its first day. Only PDBF is wired; `icab`/`idet` (the intraday-auction equivalent) use a DIFFERENT byte layout and are not ingested here.