[Apps] Fix - app-synced object should be searchable (#19206)

## Summary

- **Make app-synced objects searchable**: `isSearchable` was hardcoded
to `false` and the `searchVector` field was missing the `GENERATED
ALWAYS AS (...)` expression, causing all records to have a `NULL` search
vector and be excluded from search results. Fixed by defaulting
`isSearchable` to `true` (configurable via the object manifest),
computing the `asExpression` from the label identifier field, and
allowing the update-field-action-handler to handle the `null` → defined
`asExpression` transition.
- **Make `isSearchable` updatable on an object**: The property had
`toCompare: false` in the entity properties configuration, so updates
via the API were silently ignored and never persisted. Fixed by setting
`toCompare: true`.

packages/twenty-front/src/modules/settings/data-model/objects/forms/components/SettingsDataModelObjectIdentifiersForm.tsx

@@ -1,18 +1,21 @@
+import { isDDLLockedState } from '@/client-config/states/isDDLLockedState';
 import { useUpdateOneObjectMetadataItem } from '@/object-metadata/hooks/useUpdateOneObjectMetadataItem';
 import { type EnrichedObjectMetadataItem } from '@/object-metadata/types/EnrichedObjectMetadataItem';
 import { getActiveFieldMetadataItems } from '@/object-metadata/utils/getActiveFieldMetadataItems';
 import { objectMetadataItemSchema } from '@/object-metadata/validation-schemas/objectMetadataItemSchema';
-import { isDDLLockedState } from '@/client-config/states/isDDLLockedState';
 import { isObjectMetadataReadOnly } from '@/object-record/read-only/utils/isObjectMetadataReadOnly';
 import { Select } from '@/ui/input/components/Select';
-import { styled } from '@linaria/react';
 import { useAtomStateValue } from '@/ui/utilities/state/jotai/hooks/useAtomStateValue';
 import { zodResolver } from '@hookform/resolvers/zod';
+import { styled } from '@linaria/react';
 import { t } from '@lingui/core/macro';
 import { useMemo } from 'react';
 import { Controller, useForm } from 'react-hook-form';
 import { useNavigate } from 'react-router-dom';
-import { isLabelIdentifierFieldMetadataTypes } from 'twenty-shared/utils';
+import {
+  isLabelIdentifierFieldMetadataTypes,
+  isSearchableFieldType,
+} from 'twenty-shared/utils';
 import { IconCircleOff, IconPlus, useIcons } from 'twenty-ui/display';
 import { type SelectOption } from 'twenty-ui/input';
 import { themeCssVariables } from 'twenty-ui/theme-constants';
@@ -76,7 +79,8 @@ export const SettingsDataModelObjectIdentifiersForm = ({
       getActiveFieldMetadataItems(objectMetadataItem)
         .filter(
           ({ id, type }) =>
-            isLabelIdentifierFieldMetadataTypes(type) ||
+            (isLabelIdentifierFieldMetadataTypes(type) &&
+              isSearchableFieldType(type)) ||
             objectMetadataItem.labelIdentifierFieldMetadataId === id,
         )
         .map<SelectOption<string | null>>((fieldMetadataItem) => ({