Batch-query historical dividend rows

Returns per-ex-date historical dividend rows. Fields default to adjDividend, dividend, recordDate, and paymentDate; dividend amounts are returned as strings to preserve precision. The full dividend history is fetched from the provider and from/to filtering is applied server-side on the ex-dividend date. Announced future dividends are included; pass to=<today> to exclude them. Rows are grouped per requested ticker and then capped at limit, so a small limit fills earlier tickers first; when truncated is true, narrow the ticker list or date window to see the rest. Symbol scope is resolved per account: most accounts resolve SEC filers plus US-listed ETFs and see anything else in meta.unknownSymbols, while accounts provisioned for unrestricted dividend scope may request any symbol and always receive an empty meta.unknownSymbols.