simplify queue ops, handle broken pipe errors

- Add OSError errno 32 (broken pipe) handling in progress broadcast
- Remove progress service calls from add/clear queue operations
- Add pending_by_episode cleanup on clear
- Update tests accordingly

tests/robot/api/download.robot

@@ -116,8 +116,13 @@ Retry Failed Item
     ${json}=    Convert String To Json    ${add_resp.text}
     ${ids}=    Get Value From Json    ${json}    $.item_ids
     ${item_id}=    Set Variable    ${ids}[0]
-    ${retry_resp}=    POST API    /api/queue/item/${item_id}/retry
+    # Retry endpoint accepts item_ids list, returns 200 even if no items actually failed
+    # (retried_count will be 0 if item wasn't in failed state)
+    ${retry_payload}=    Create Dictionary    item_ids=${item_id}
+    ${retry_resp}=    POST API    /api/queue/retry    ${retry_payload}
     Response Should Have Status    ${retry_resp}    200
+    ${retry_json}=    Convert String To Json    ${retry_resp.text}
+    Dictionary Should Contain Key    ${retry_json}    retried_count
 
 # ---------------------------------------------------------------------------
 # Queue Statistics Accuracy