Drop per-task port blocks; previews use any free loopback port

mac/Sources/Byre/Panes.swift

@@ -305,7 +305,7 @@ private struct TaskBar: View {
         }
         .onAppear {
             off = store.events.add { ev in
-                if ev.kind == "preview.exposed" && ev.taskId == store.selectedTaskId {
+                if (ev.kind == "preview.exposed" || ev.kind == "preview.taken") && ev.taskId == store.selectedTaskId {
                     Task {
                         await load()
                     }

mac/Sources/Byre/Store.swift

@@ -824,7 +824,7 @@ final class Store {
             spawn("load inbox") {
                 try await self.loadInbox()
             }
-        case "preview.exposed":
+        case "preview.exposed", "preview.taken":
             if let taskId = ev.taskId {
                 Task {
                     await forwards.load(api, taskId)

mac/Sources/Byre/TranscriptBuilder.swift

@@ -957,6 +957,9 @@ final class TranscriptBuilder {
         case "preview.exposed":
             return note([.text("\(ev.actor) exposed \"\(jsString(p["name"]))\" at "), .preview(taskId: ev.taskId ?? "", port: int(p, "port") ?? 0)])
 
+        case "preview.taken":
+            return note([.text("\"\(jsString(p["name"]))\" stopped: "), .task(str(p, "by_task_id") ?? ""), .text(" now serves port \(int(p, "port") ?? 0)")])
+
         case "task.merged":
             let commit = str(p, "commit") ?? ""
             if let parentTask = str(p, "parent_task_id") {