Show a merge's push to the remote while it runs

mac/Sources/Byre/Store.swift

@@ -40,6 +40,7 @@ struct TaskState {
 private let stateTitles: [ByreTask.StatePayload: TaskState] = [
     .asking: TaskState(kind: .answer, label: "Needs your answer", title: "The agent asked a question"),
     .merging: TaskState(kind: .merging, label: "Merging", title: "The merge is under way"),
+    .pushing: TaskState(kind: .merging, label: "Pushing", title: "byre is pushing the merge commit to the remote"),
     .mergeHeld: TaskState(kind: .held, label: "Merge held", title: "Waiting for the merge in progress in this project to finish"),
     .mergeAfterReview: TaskState(kind: .held, label: "Merge after review", title: "Merges when the running review finishes with no findings"),
     .running: TaskState(kind: .working, label: "Working", title: "The agent is mid-turn or its subagents are running"),

mac/Sources/Byre/TranscriptBuilder.swift

@@ -965,6 +965,9 @@ final class TranscriptBuilder {
             let pushed = str(p, "pushed") ?? ""
             return note([.text("✓ \(ev.actor) merged the task\(commit.isEmpty ? "" : " as \(commit.prefix(7))")\(pushed.isEmpty ? "" : " and pushed it to \(pushed)")")], .ok)
 
+        case "task.pushing":
+            return note([.text("pushing \(jsString(p["commit"]).prefix(7)) to \(jsString(p["pushed"]))…")])
+
         case "task.merged_to_main":
             return note([.text("\(ev.actor) merged the work so far as \(jsString(p["commit"]).prefix(7)), \"\(jsString(p["merge_title"]))\", pushed it to \(jsString(p["pushed"])) and kept the task open")])