fix(spec): take the next free step-18 orders after the element:text variant landing

The element:text variant retirement landed at conversion order 59 and
rationale order 68; this retirement moves to 60 and 69.

Claude-Session: https://claude.ai/code/session_01T9u38rswFp5Rw8DswRUReJ
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

packages/spec/src/conversions/registry.ts

@@ -14800,7 +14800,7 @@ const MAJOR_18_CONVERSIONS: readonly OrderedConversion[] = [
   { conversion: objectGridDefaultSortRemoved, order: 14 },
   { conversion: objectGridResizableColumnsRemoved, order: 57 },
   { conversion: objectKanbanQuickAddRemoved, order: 15 },
-  { conversion: objectMasterDetailFormDetailSortFieldRemoved, order: 59 },
+  { conversion: objectMasterDetailFormDetailSortFieldRemoved, order: 60 },
   { conversion: objectTenancyOrganizationFieldRemoved, order: 35 },
   { conversion: pageAssignedProfilesRemoved, order: 31 },
   { conversion: pageComponentFilterRecordToRuleArray, order: 36 },

packages/spec/src/migrations/registry.ts

@@ -5854,7 +5854,7 @@ const STEP18_RATIONALE: readonly RationaleFragment[] = [
   },
   {
     id: 'object-master-detail-form-detail-sort-field-retired',
-    order: 68,
+    order: 69,
     text:
       'It also retires an `object-master-detail-form` detail entry\'s `sortField` (#21589, ADR-0049 '
       + 'enforce-or-remove; the spec half of objectui#11070 round 9). The console stopped reading the '