Add system view fallback (#18536)

## Context
The goal is to add a "See records" button in all objects that would
redirect to that view (this will be done in a later PR). See screenshot
below.
<img width="665" height="312" alt="Screenshot 2026-03-10 at 15 54 36"
src="https://github.com/user-attachments/assets/6e23a75b-cff0-4d93-bce8-b5481b05c6f6"
/>

## Implementation
- If a view does not exist on an object, there is a **temporary**
fallback where the frontend creates the missing view as a custom view
when going over the object index page
- System objects are now surfaced but we don't want their records to be
editable, they will be readonly (mostly, all fields will be non-editable
except for their custom fields).
- We can't create a new record of a system object, some actions are also
hidden.
- The backend now rejects if you are trying to delete the last view of
an object

packages/twenty-front/src/modules/object-record/object-options-dropdown/components/ObjectOptionsDropdownCustomView.tsx

@@ -14,11 +14,13 @@ import { selectedItemIdComponentState } from '@/ui/layout/selectable-list/states
 import { useAtomComponentStateValue } from '@/ui/utilities/state/jotai/hooks/useAtomComponentStateValue';
 import { useSetAtomComponentState } from '@/ui/utilities/state/jotai/hooks/useSetAtomComponentState';
 import { useGetCurrentViewOnly } from '@/views/hooks/useGetCurrentViewOnly';
+import { coreViewsFromObjectMetadataItemFamilySelector } from '@/views/states/selectors/coreViewsFromObjectMetadataItemFamilySelector';
 import { ViewKey } from '@/views/types/ViewKey';
 import { ViewType, viewTypeIconMapping } from '@/views/types/ViewType';
 import { useDestroyViewFromCurrentState } from '@/views/view-picker/hooks/useDestroyViewFromCurrentState';
 import { viewPickerReferenceViewIdComponentState } from '@/views/view-picker/states/viewPickerReferenceViewIdComponentState';
 import { useAtomStateValue } from '@/ui/utilities/state/jotai/hooks/useAtomStateValue';
+import { useAtomFamilySelectorValue } from '@/ui/utilities/state/jotai/hooks/useAtomFamilySelectorValue';
 import { useLingui } from '@lingui/react/macro';
 import { capitalize, isDefined } from 'twenty-shared/utils';
 import {
@@ -64,7 +66,13 @@ export const ObjectOptionsDropdownCustomView = ({
       )
     : undefined;
 
+  const viewsOnCurrentObject = useAtomFamilySelectorValue(
+    coreViewsFromObjectMetadataItemFamilySelector,
+    { objectMetadataItemId: objectMetadataItem.id },
+  );
+
   const isDefaultView = currentView?.key === ViewKey.Index;
+  const isLastView = viewsOnCurrentObject.length <= 1;
 
   const recordIndexCalendarLayout = useAtomStateValue(
     recordIndexCalendarLayoutState,
@@ -272,14 +280,18 @@ export const ObjectOptionsDropdownCustomView = ({
                 onClick={() => handleDelete()}
                 LeftIcon={IconTrash}
                 text={t`Delete view`}
-                disabled={isDefaultView}
+                disabled={isDefaultView || isLastView}
               />
             </SelectableListItem>
           </div>
-          {isDefaultView && (
+          {(isDefaultView || isLastView) && (
             <AppTooltip
               anchorSelect={`#delete-view-menu-item`}
-              content={t`Not available on Default View`}
+              content={
+                isDefaultView
+                  ? t`Not available on Default View`
+                  : t`Cannot delete the only view`
+              }
               noArrow
               place="bottom"
               width="100%"