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/activities/calendar/components/CalendarEventDetails.tsx

@@ -157,10 +157,12 @@ export const CalendarEventDetails = ({
   const renderField = (fieldMetadataItem: FieldMetadataItem) => {
     const isReadOnly = isRecordFieldReadOnly({
       isRecordReadOnly,
+      isSystemObject: objectMetadataItem.isSystem,
       objectPermissions,
       fieldMetadataItem: {
         id: fieldMetadataItem.id,
         isUIReadOnly: fieldMetadataItem.isUIReadOnly ?? false,
+        isCustom: fieldMetadataItem.isCustom ?? false,
       },
     });