Add a Captures tab showing screen captures from the task's agent

mac/Sources/Byre/Store.swift

@@ -3,10 +3,10 @@ import Observation
 import SwiftData
 
 enum TaskTab: String {
-    case transcript, board, changes, files, page, terminal, workflow
+    case transcript, board, changes, files, page, captures, terminal, workflow
 }
 
-let taskTabs: [TaskTab] = [.transcript, .board, .changes, .files, .page, .terminal, .workflow]
+let taskTabs: [TaskTab] = [.transcript, .board, .changes, .files, .page, .captures, .terminal, .workflow]
 
 enum JumpTarget: Equatable {
     case question(String)
@@ -215,6 +215,10 @@ final class Store {
         selectedTaskId.flatMap { taskFeeds[$0] }
     }
 
+    func captures(_ taskId: String) -> [Capture] {
+        taskFeeds[taskId]?.captures ?? []
+    }
+
     func activeTasks() -> [(project: Project, task: ByreTask)] {
         projects.flatMap { project in
             (tasks[project.id] ?? []).filter { $0.status == .active }.map { (project, $0) }