Function sync_issue_dependencies 

pub async fn sync_issue_dependencies(
    backend: &dyn ExternalBackend,
    store: &TaskStore,
    task_id: i64,
    repo: &str,
    issue_number: Option<i64>,
    body: &str,
) -> Result<SyncOutcome>

Replace one issue’s dependency rows from the native blocked-by links and the issue body.

Both sources are stored, deduplicated by repository and number. A cli row is carried over, and a failed read keeps every stored row