fix: hide unlinked old activities from current work

Imported follow-ups with no person, company, or deal stayed on the board because only linked prior records were archived.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/test/prior-archive.test.ts

@@ -61,6 +61,12 @@ describe('بایگانی اطلاعات قبل', () => {
         OR: [{ importSource: 'didar' }, { previousImportSource: 'didar' }],
       },
     });
+    assert.deepEqual(linked.OR[3], {
+      personId: null,
+      companyId: null,
+      dealId: null,
+      dueAt: { lt: cutoff.toISOString() },
+    });
     assert.deepEqual(current.OR[1], { status: 'open', dueAt: { gt: now.toISOString() } });
 
     const archive = JSON.parse(JSON.stringify(activityPriorWhere('archive', now, cutoff))) as {