feat(background-task): track retry attempts across sessions

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/features/background-agent/constants.ts

@@ -45,6 +45,7 @@ export interface Todo {
 }
 
 export interface QueueItem {
+  attemptID: string
   task: BackgroundTask
   input: LaunchInput
 }