fix(api): keep data.truncated on the account activity feed, deprecated

v1.43.6 shipped truncated as a required field of the activity
response's data, and moving it to meta alone would break a client
built against that in a patch release. data.truncated is back with the
same value as meta.truncated and is marked deprecated in the spec; the
web client keeps reading meta.

docs/api/openapi.yaml

@@ -21437,8 +21437,9 @@ paths:
         per day with a count, rather than one per request. `retentionDays` rides the response because audit history is
         purged on a schedule the operator configures: a view that showed the rows without the window would imply a
         completeness it does not have, and clients must state the number the server sends rather than assume the 365-day
-        default. Whether the list stopped at its row ceiling is `meta.truncated` (it was a `truncated` field in `data`
-        before v1.43.7). Not delegable: a grant is not an introduction to the other people in the household."
+        default. Whether the list stopped at its row ceiling is `meta.truncated`; the `truncated` field in `data`
+        carries the same value and is deprecated. Not delegable: a grant is not an introduction to the other people in
+        the household."
       responses:
         "200":
           description: The activity, and how far back it can see.
@@ -81393,9 +81394,15 @@ components:
           description: How far back this feed can see, in days. Resolved from the instance's audit retention setting (365 by
             default, operator-configurable), NOT a constant — an instance running a 90-day window sends 90. The query is
             bounded to this window, so it is the real limit of the list and not only a caption. Show it beside the rows.
+        truncated:
+          type: boolean
+          deprecated: true
+          description: "Deprecated: read `meta.truncated`, which carries the same value. Whether the list stopped at its row
+            ceiling; kept in `data` for clients built against v1.43.6 and earlier."
       required:
         - entries
         - retentionDays
+        - truncated
       additionalProperties: false
       description: The owner's record of what somebody else did in their record, bounded by the instance's audit retention.
     RecordActivityEntry: