Update Document

Updates the document with the provided changeset. - Gas accounting (when & what is charged): - Base step charge (once per run of this step): 40 + 5 × changesetLength. - Expression/template resolution under "/changeset/**" (if present): - For each standalone expression ${…}: 5 + ceil(bytes(expr)/100). - For each template string containing one or more ${…} placeholders: 3 × placeholderCount + ceil(bytes(template)/100). - Any document(<pointer>) used inside expressions/templates charges per call: 8 + depth(pointer) + ceil(snapshotBytes/100). - Per change (applied in order after boundary validation): - Boundary check: 2. - Operation charge: - add or replace: 20 + ceil(valueBytes/100) (valueBytes is the canonical JSON size of val). - remove: 10. - Cascade routing (Document Update delivery): 10 × N, where N is the number of scopes that receive the resulting Document Update (origin scope and each participating ancestor up to root).