appendRows orders each record by the source’s exact headers and appends it to
the body.
Example
Inputs
spreadsheet, source, and one record or non-empty records array are required.
Source syntax is described by List rows.
Values are string, number, boolean, or null. Record keys must exactly match
headers; omitted columns become null. inputMode defaults to userEntered,
which parses formula strings; raw stores them literally.
account optionally selects the Google account binding.
Output
Returns{ affectedCells, rowNumbers, updatedRange? }. rowNumbers is empty
because Google append APIs do not reliably return row identities. Ordinary
sheets can return updatedRange; native-table appends do not.