Allow merge-based update-branch flow in PR assistant guidance

.github/workflows/agentics-maintenance.yml

@@ -42,9 +42,9 @@ on:
         description: 'Optional maintenance operation to run'
         required: false
         type: choice
-        default: 'none'
+        default: ''
         options:
-          - 'none'
+          - ''
           - 'disable'
           - 'enable'
           - 'update'
@@ -54,7 +54,7 @@ permissions: {}
 
 jobs:
   close-expired-entities:
-    if: ${{ !github.event.repository.fork && (github.event_name != 'workflow_dispatch' || github.event.inputs.operation == 'none') }}
+    if: ${{ !github.event.repository.fork && (github.event_name != 'workflow_dispatch' || github.event.inputs.operation == '') }}
     runs-on: ubuntu-slim
     permissions:
       discussions: write
@@ -94,7 +94,7 @@ jobs:
             await main();
 
   run_operation:
-    if: ${{ github.event_name == 'workflow_dispatch' && github.event.inputs.operation != 'none' && !github.event.repository.fork }}
+    if: ${{ github.event_name == 'workflow_dispatch' && github.event.inputs.operation != '' && !github.event.repository.fork }}
     runs-on: ubuntu-slim
     permissions:
       actions: write