fix: restore ViewFilter value stringification lost in converter removal (#18745)

## Summary

- **Restores `convertViewFilterValueToString()` calls** that were lost
when the converter layer was removed in #18667. The GraphQL
`ViewFilter.value` is typed as `JSON` (can be a string, array, or
object), but the frontend type system expects a `string`. Without
stringification, SELECT/MULTI_SELECT filter values (e.g. `['LOST']`)
reach `arrayOfStringsOrVariablesSchema` as raw arrays, causing a
`ZodError: expected string, received array`.
- **Fixes applied at two data boundary points**: `splitViewWithRelated`
(primary entry from metadata store) and `mapViewFiltersToFilters` (which
also accepts `GqlViewFilter[]` directly).

Fixes a production regression introduced by #18667.

## Test plan

- [ ] Apply a SELECT filter (e.g. filter Opportunities by Stage =
"Lost") — should no longer throw ZodError
- [ ] Apply a MULTI_SELECT filter — should work correctly
- [ ] Verify filters with multiple selected values work (e.g. Stage is
"Lost" or "Won")
- [ ] Verify empty filters and "is not" operands still work
- [ ] Verify filters loaded from saved views still work after page
refresh


Made with [Cursor](https://cursor.com)

packages/twenty-front/src/modules/metadata-store/utils/splitViewWithRelated.ts

@@ -6,6 +6,7 @@ import { type FlatViewFilterGroup } from '@/metadata-store/types/FlatViewFilterG
 import { type FlatViewGroup } from '@/metadata-store/types/FlatViewGroup';
 import { type FlatViewSort } from '@/metadata-store/types/FlatViewSort';
 import { type ViewWithRelations } from '@/views/types/ViewWithRelations';
+import { convertViewFilterValueToString } from 'twenty-shared/utils';
 
 type SplitResult = {
   flatViews: FlatView[];
@@ -51,6 +52,7 @@ export const splitViewWithRelated = (
     for (const viewFilter of viewFilters) {
       flatViewFilters.push({
         ...viewFilter,
+        value: convertViewFilterValueToString(viewFilter.value),
         viewId: viewWithRelated.id,
       });
     }

packages/twenty-front/src/modules/views/utils/mapViewFiltersToFilters.ts

@@ -4,7 +4,11 @@ import { type FieldMetadataItem } from '@/object-metadata/types/FieldMetadataIte
 
 import { isSystemSearchVectorField } from '@/object-record/utils/isSystemSearchVectorField';
 import { type CompositeFieldSubFieldName } from '@/settings/data-model/types/CompositeFieldSubFieldName';
-import { getFilterTypeFromFieldType, isDefined } from 'twenty-shared/utils';
+import {
+  convertViewFilterValueToString,
+  getFilterTypeFromFieldType,
+  isDefined,
+} from 'twenty-shared/utils';
 import { type ViewFilter as GqlViewFilter } from '~/generated-metadata/graphql';
 import { type ViewFilter } from '@/views/types/ViewFilter';
 
@@ -34,14 +38,16 @@ export const mapViewFiltersToFilters = (
 
       const operand = viewFilter.operand;
 
+      const stringValue = convertViewFilterValueToString(viewFilter.value);
+
       return {
         id: viewFilter.id,
         fieldMetadataId: viewFilter.fieldMetadataId,
-        value: viewFilter.value,
+        value: stringValue,
         displayValue:
-          'displayValue' in viewFilter
+          'displayValue' in viewFilter && isDefined(viewFilter.displayValue)
             ? viewFilter.displayValue
-            : viewFilter.value,
+            : stringValue,
         operand,
         recordFilterGroupId: viewFilter.viewFilterGroupId ?? undefined,
         positionInRecordFilterGroup: viewFilter.positionInViewFilterGroup,