fix(computer): reap mac helper after client loss (#11425)

native/computer-use-macos/Sources/OrcaComputerUseMacOSCore/AgentSessionOwnership.swift

@@ -0,0 +1,19 @@
+public struct AgentSessionOwnership: Sendable {
+    private var authenticatedConnections: Set<Int32> = []
+    private var wasClaimed = false
+
+    public init() {}
+
+    public mutating func registerConnection(_ connection: Int32, authenticated: Bool) -> Bool {
+        guard authenticated else { return false }
+        let inserted = authenticatedConnections.insert(connection).inserted
+        guard inserted, !wasClaimed else { return false }
+        wasClaimed = true
+        return true
+    }
+
+    public mutating func disconnect(_ connection: Int32) -> Bool {
+        guard authenticatedConnections.remove(connection) != nil else { return false }
+        return wasClaimed && authenticatedConnections.isEmpty
+    }
+}