fix(maintenance): list each prompt the Pair repair kept (#550)

The job counted its protected prompts but listed none, so Protected 2 opened
an empty group. The apply now returns one row per kept prompt with the
review's reasons, in its order ("Prompt 7: kept, pairs disagree on category:
Adult, asian"), and the job keeps them all for the report.

py/api/maintenance.py

@@ -697,7 +697,19 @@ class MaintenanceRoutesMixin:
             rows,
             complete=plan.operation in COMPLETE_RECORD,
         )
-        job.record_counted("protected", payload["protected"])
+        if "kept" in result:
+            # #550: each kept record with its reason, like the changed ones.
+            kept = [
+                {
+                    "path": "",
+                    "detail": f"Prompt {item['prompt_id']}: kept, "
+                    + "; ".join(item["reasons"]),
+                }
+                for item in result["kept"]
+            ]
+            job.record_counted("protected", len(kept), kept, complete=True)
+        else:
+            job.record_counted("protected", payload["protected"])
         line = _changed_line(
             plan.operation, result["changed"], result.get("marks", 0), result
         )