fix: the date fields of the product teaser group plugin are datetime fields

settings.dateFrom and settings.dateTo were still type=input with eval=date.
TYPO3 13 only migrates renderType=inputDateTime to type=datetime, so these
were rendered as text inputs whose JavaScript expects an ISO 8601 value. It
got the stored timestamp (e.g. 1793491200), threw "Invalid ISO8601 DateTime
string", and the edit form of these plugin elements never finished loading.

The datetime element converts the stored timestamps itself and, without a
dbType, saves timestamps again, so stored values and the frontend stay as
they are.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/ep_products/Configuration/FlexForms/flexform_product_teaser.xml

@@ -121,9 +121,8 @@
                             <![CDATA[FIELD:switchableControllerActions:=:Product->teasergroup]]>
                         </displayCond>
                         <config>
-                            <type>input</type>
-                            <size>10</size>
-                            <eval>date</eval>
+                            <type>datetime</type>
+                            <format>date</format>
                         </config>
                     </settings.dateFrom>
                     <settings.dateTo>
@@ -132,9 +131,8 @@
                             <![CDATA[FIELD:switchableControllerActions:=:Product->teasergroup]]>
                         </displayCond>
                         <config>
-                            <type>input</type>
-                            <size>10</size>
-                            <eval>date</eval>
+                            <type>datetime</type>
+                            <format>date</format>
                         </config>
                     </settings.dateTo>
                     <settings.productUid>