Watch: the Subagents section on the thread screen collapses behind a header with the count and how many wait or work, and opens on its own when one waits

watch/WristCodeTests/SnapshotTests.swift

@@ -127,6 +127,7 @@ struct SnapshotTests {
     @Test func threadWithSubagents() async throws {
         let detail = try await DemoGateway().thread(hostId: "server-gib", threadId: "t-container")
         try write(titled("Thread", ThreadView(hostId: "server-gib", threadId: "t-container", detail: detail, scrolls: false)), "thread-subagents.png")
+        try write(titled("Thread", ThreadView(hostId: "server-gib", threadId: "t-container", detail: detail, subagentsOpen: true, scrolls: false)), "thread-subagents-open.png")
     }
 
     @Test func threadWithEarlierAndMarkdown() async throws {