Allow custom fields to be editable for system objects and prevent the error for timeline activity on system object pages. (#16268)

Solves #16015 

- Added a check in `useTimelineActivities.ts` to see if the system
object page we're viewing has timelineActivity being tracked before
querying to get the activity history.
- Removed @WorkspaceIsObjectUIReadOnly decorator from system objects and
added @WorkspaceIsFieldUIReadOnly to standard and system fields to allow
custom field edits as requested in the issue.
- Did not add calendarEvents or other system objects to timelineActivity
just yet since keeping track of timeline activity for every one of them
felt counter-intuitive and bloated. In order to determine which objects
need timelineActivity, I think we need to fix the broken views of system
objects first, such as the one in the attached screenshots - a good
number of them are broken. The check I added to
`useTimelineActivities.ts` hook displays timeline activity as empty for
the time - error would not be shown as suggested by Thomas.

<img width="1062" height="858" alt="image"
src="https://github.com/user-attachments/assets/e877e0fe-b665-46e3-b785-e84f2af7f833"
/>

<br />

<img width="1061" height="858" alt="image"
src="https://github.com/user-attachments/assets/0eba8c1c-444a-4b13-beda-64b95cf39077"
/>

- Editing custom fields on calendar events (and other objects without
position fields) crashed with TypeError: Cannot convert undefined or
null to object in sortCachedObjectEdges. This happened because some
cached queries had empty orderBy arrays ([]), and the optimistic effect
tried to sort with them. Objects without position fields returned
empty orderBy arrays when there were no sorts, while objects with
position fields automatically got [{ position: 'AscNullsFirst' }].
The backend always adds { id: 'AscNullsFirst' } as a fallback, but
the frontend didn't match this. So, I added { id: 'AscNullsFirst' } to
the Frontend as default orderBy when there are no sorts and no position
field.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Apply per-field UI read-only to system/standard fields and skip
timeline activity fetching when the target object isn’t related; refine
record-table cell open/navigation behavior.
> 
> - Server: Replace object-level UI read-only with per-field
`isUIReadOnly` across many standard objects (e.g., `calendarEvent`,
`workspaceMember`, messaging, calendar, favorites, attachments,
workflows, etc.), and mirror this via `@WorkspaceIsFieldUIReadOnly` on
workspace entities.
> - Frontend: In `useTimelineActivities.ts`, check object metadata for a
relation to `timelineActivity` and `skip` the query when absent,
preventing errors on system object pages.
> - Frontend: Simplify/adjust record-table cell logic—remove unused
args, allow navigation from first column when non-empty, block editing
for read-only records (while still allowing navigation), and update
button handlers/hover styles accordingly.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
dac1262d70d97ce84b39730454dd3579c494994a. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Co-authored-by: Félix Malfait <felix@twenty.com>

packages/twenty-front/src/modules/activities/timeline-activities/hooks/useTimelineActivities.ts

@@ -2,6 +2,7 @@ import { useLinkedObjectsTitle } from '@/activities/timeline-activities/hooks/us
 import { type TimelineActivity } from '@/activities/timeline-activities/types/TimelineActivity';
 import { type ActivityTargetableObject } from '@/activities/types/ActivityTargetableEntity';
 import { getActivityTargetObjectFieldIdName } from '@/activities/utils/getActivityTargetObjectFieldIdName';
+import { useObjectMetadataItem } from '@/object-metadata/hooks/useObjectMetadataItem';
 import { CoreObjectNameSingular } from '@/object-metadata/types/CoreObjectNameSingular';
 import { useGenerateDepthRecordGqlFieldsFromObject } from '@/object-record/graphql/record-gql-fields/hooks/useGenerateDepthRecordGqlFieldsFromObject';
 import { useFindManyRecords } from '@/object-record/hooks/useFindManyRecords';
@@ -23,6 +24,17 @@ export const useTimelineActivities = (
         nameSingular: targetableObject.targetObjectNameSingular,
       });
 
+  const { objectMetadataItem: timelineActivityMetadata } =
+    useObjectMetadataItem({
+      objectNameSingular: CoreObjectNameSingular.TimelineActivity,
+    });
+
+  const hasTimelineActivityField = timelineActivityMetadata.fields.some(
+    (field) =>
+      field.relation?.targetObjectMetadata?.nameSingular ===
+      targetableObject.targetObjectNameSingular,
+  );
+
   const { recordGqlFields: depthOneRecordGqlFields } =
     useGenerateDepthRecordGqlFieldsFromObject({
       objectNameSingular: CoreObjectNameSingular.TimelineActivity,
@@ -34,6 +46,7 @@ export const useTimelineActivities = (
     loading: loadingTimelineActivities,
     fetchMoreRecords,
   } = useFindManyRecords<TimelineActivity>({
+    skip: !hasTimelineActivityField,
     objectNameSingular: CoreObjectNameSingular.TimelineActivity,
     filter: {
       [targetableObjectFieldIdName]: {