improve update with better per property per row granularity

• Improve query.update() dropping a column from the whole batch whenever the first row didn't provide it, even if other rows in the same batch did (e.g. rows sent with only the properties that actually changed). The column-inclusion check now looks across all rows instead of only rows[0], and rows that omit a given property keep their current database value for that column instead of being forced to NULL.
• Add exported SqlValue type (string | number | boolean | Date | number[] | null) representing any scalar value usable as a query parameter or row/column value. Replaces the internal/public Filter["value"] pattern used across query.select(), query.update(), query.insert(), query.upsert(), query.archive(), filter() and execute(). Also fixes execute()'s public declaration, which previously omitted null from its inline argument type.