Renders a dynamic list of sub-reports by iterating over query rows and expanding each as a {report:...} macro.
Report — set as ReportType in def_report.
def Render(self, Param1="", Param2="", Param3="") -> str:
Returns the concatenated HTML output of all sub-reports. The query must return at least one column: the report code to embed. An optional second column provides the sub-report's Param1. Each row is expanded via process_text("{report:CODE:PARAM1}").