Add Studio run interrupt, confirm actions, and template-bound controls.

AbortController cancels message/reroll streams; undo/reroll use in-place confirm; runControls in skill templates gate UI by skillId.

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

data/agent/skill_templates.json

@@ -25,7 +25,8 @@
       "supportsLoopUntilSatisfied": false,
       "supportsInputs": false,
       "supportsInsertion": false,
-      "supportsScoring": false
+      "supportsScoring": false,
+      "runControls": []
     },
     {
       "skillId": "studio.worldbook_entry",
@@ -67,7 +68,8 @@
           "enabled": true,
           "dimensions": []
         }
-      }
+      },
+      "runControls": ["undo", "reroll", "interrupt", "nextStep", "questions"]
     }
   ]
 }