Support morph relations in workflow record nodes (#21403)

## Support morph (polymorphic) relations in workflow record nodes

Morph relations (e.g. a polymorphic `Owner` on `Pet` targeting `Person`
or `Company`) were not selectable in the workflow **Create / Update /
Upsert Record** nodes. This PR adds full support for setting them.

### What changed

**Frontend**
- `shouldDisplayFormField`: allow `MORPH_RELATION` (many-to-one) so
morph fields appear in record forms.
- New `FormMorphRelationToOneFieldInput`: a polymorphic record picker
across the morph's target objects, storing a self-describing value `{
targetObjectMetadataId, id }`.
- Wired the morph branch into `FormFieldInput`.

**Backend**
- New `formatWorkflowRecordMorphRelationFields` util: resolves the form
value (stored under the base field name, e.g. `owner`) into the correct
per-target join column (`ownerCompanyId`), nulling siblings to keep
exactly one target referenced.
- Wired into the create / update / upsert workflow actions (update also
expands `fieldsToUpdate` to the concrete join columns).

### Permissions handling
- The picker's search is scoped to only the morph targets the user can
read (`canReadObjectRecords`), so it no longer breaks when a target
object is inaccessible.
- If an existing value points to an object the user can't read, the
field shows the reused **"Not shared"** lock display instead of an empty
field, while remaining editable when other targets are readable.

### Notes
- No data schema / migration changes — reuses the existing per-target
morph columns and stores the selection in the existing workflow step
JSON settings.

<img width="607" height="717" alt="Screenshot 2026-06-10 at 14 57 40"
src="https://github.com/user-attachments/assets/496442a1-04a5-40f8-8b56-b28e38b00d5a"
/>

Also handles the case where the selected record is not readable
<img width="596" height="737" alt="image"
src="https://github.com/user-attachments/assets/c5ffb94e-3838-4db5-853e-f8e490331f23"
/>

packages/twenty-front/src/modules/workflow/workflow-variables/components/WorkflowVariablePicker.tsx

@@ -63,6 +63,7 @@ export const WorkflowVariablePicker: VariablePickerComponent = ({
   onVariableSelect,
   shouldDisplayRecordObjects = false,
   shouldDisplayRecordFields = true,
+  objectNameSingularsToSelect,
 }) => {
   const dropdownId = `${SEARCH_VARIABLES_DROPDOWN_ID}-${instanceId}`;
   const isDropdownOpen = useAtomComponentStateValue(
@@ -82,6 +83,7 @@ export const WorkflowVariablePicker: VariablePickerComponent = ({
         disabled={disabled}
         shouldDisplayRecordObjects={shouldDisplayRecordObjects}
         shouldDisplayRecordFields={shouldDisplayRecordFields}
+        objectNameSingularsToSelect={objectNameSingularsToSelect}
       />
     </StyledSearchVariablesDropdownContainer>
   );

packages/twenty-front/src/modules/workflow/workflow-variables/components/WorkflowVariablesDropdown.tsx

@@ -39,6 +39,7 @@ export const WorkflowVariablesDropdown = ({
   onVariableSelect,
   shouldDisplayRecordFields,
   shouldDisplayRecordObjects,
+  objectNameSingularsToSelect,
 }: {
   clickableComponent?: React.ReactNode;
   disabled?: boolean;
@@ -47,6 +48,7 @@ export const WorkflowVariablesDropdown = ({
   onVariableSelect: (variableName: string) => void;
   shouldDisplayRecordFields: boolean;
   shouldDisplayRecordObjects: boolean;
+  objectNameSingularsToSelect?: string[];
 }) => {
   const { theme } = useContext(ThemeContext);
   const dropdownId = `${SEARCH_VARIABLES_DROPDOWN_ID}-${instanceId}`;
@@ -119,6 +121,7 @@ export const WorkflowVariablesDropdown = ({
             onSelect={handleSubItemSelect}
             onBack={handleBack}
             shouldDisplayRecordObjects={shouldDisplayRecordObjects}
+            objectNameSingularsToSelect={objectNameSingularsToSelect}
           />
         )
       }

packages/twenty-front/src/modules/workflow/workflow-variables/components/WorkflowVariablesDropdownStepItems.tsx

@@ -29,6 +29,7 @@ type WorkflowVariablesDropdownStepItemsProps = {
   onSelect: (value: string) => void;
   onBack: () => void;
   shouldDisplayRecordObjects: boolean;
+  objectNameSingularsToSelect?: string[];
 };
 
 export const WorkflowVariablesDropdownStepItems = ({
@@ -36,6 +37,7 @@ export const WorkflowVariablesDropdownStepItems = ({
   onSelect,
   onBack,
   shouldDisplayRecordObjects,
+  objectNameSingularsToSelect,
 }: WorkflowVariablesDropdownStepItemsProps) => {
   const { t } = useLingui();
   const { getIcon } = useIcons();
@@ -97,8 +99,18 @@ export const WorkflowVariablesDropdownStepItems = ({
     : true;
 
   const objectLabel = displayedSubStepObjectMetadata?.labelSingular;
+
+  const isSubStepObjectSelectable =
+    !isDefined(objectNameSingularsToSelect) ||
+    (isDefined(displayedSubStepObjectMetadata) &&
+      objectNameSingularsToSelect.includes(
+        displayedSubStepObjectMetadata.nameSingular,
+      ));
+
   const shouldDisplaySubStepObject =
-    shouldDisplayRecordObjects && isObjectFoundThroughSearch;
+    shouldDisplayRecordObjects &&
+    isObjectFoundThroughSearch &&
+    isSubStepObjectSelectable;
 
   const displayedSubStepObjectIconProps = isDefined(
     displayedSubStepObjectMetadata,