feat: background tasks panel (Phase 7)

Sources/LiveKit/ControlChannel.swift

@@ -26,6 +26,7 @@ final class ControlChannel: NSObject, RoomDelegate {
         let content: String?
         let result: String?
         let error: String?
+        let createdAt: Double?
     }
 
     var onEvent: ((InboundEvent) -> Void)?
@@ -63,19 +64,23 @@ final class ControlChannel: NSObject, RoomDelegate {
         }
     }
 
-    /// Inbound task_event handling (topic-agnostic per web UI). Returns true when consumed.
+    /// Inbound task_event handling (topic-agnostic per web UI). The agent publishes
+    /// {type:"task_event", task_id, event, ...} — the discriminator is `event`, not `type`.
     func handleTaskEvent(_ data: Data) -> Bool {
         guard let json = try? decoder.decode([String: JSONValue].self, from: data),
-              let type = json["type"]?.stringValue,
+              json["type"]?.stringValue == "task_event",
+              let type = json["event"]?.stringValue,
               ["created", "step", "completed", "failed"].contains(type) else { return false }
+        let taskObj = json["task"]?.objectValue ?? [:]
         let payload = TaskEventPayload(
             type: type,
             taskId: json["task_id"]?.stringValue,
-            description: json["description"]?.stringValue,
+            description: json["description"]?.stringValue ?? taskObj["description"]?.stringValue,
             role: json["role"]?.stringValue,
             content: json["content"]?.stringValue,
             result: json["result"]?.stringValue,
-            error: json["error"]?.stringValue
+            error: json["error"]?.stringValue,
+            createdAt: json["created_at"]?.doubleValue ?? taskObj["created_at"]?.doubleValue
         )
         onEvent?(.taskEvent(payload))
         return true
@@ -137,6 +142,11 @@ indirect enum JSONValue: Decodable {
         return nil
     }
 
+    var doubleValue: Double? {
+        if case .number(let value) = self { return value }
+        return nil
+    }
+
     var objectValue: [String: JSONValue]? {
         if case .object(let value) = self { return value }
         return nil