Interface KapomDeclarativeBand

a page header/footer as a declarative block tree — no raw doc callback needed. children render into the band's reserved zone on every page (via a confined context), the same block types you use in blocks. Restricted like a row/box column: no table/section inside (they'd paginate within a fixed zone). Use the full PageBand (render callback) only when you need raw jsPDF drawing the tree can't express.