Function watcher_sync

tests/daemon_suite/git_watch_test.rs:101–115

The watcher's sync-execution logic, reproduced faithfully: diff-scope from `last_synced_commit` when possible, else a full sync. This is the exact decision `git_watch::sync_project` makes; testing it here proves the freshness contract without reaching into the crate-private watcher.

(project: &Path, escalation: usize)

/// decision `git_watch::sync_project` makes; testing it here proves the freshness
/// contract without reaching into the crate-private watcher.
async fn watcher_sync(project: &Path, escalation: usize) {
    let cg = TraceDecay::open(project).await.unwrap();
    match cg.last_synced_commit().await {
        Some(base) => match cg.stale_files_since_commit(&base, escalation) {
            Some(files) if files.is_empty() => {}
            Some(files) => cg.sync_if_stale_silent(&files).await.unwrap(),
            None => {
                cg.sync().await.unwrap();
            }
        },
        None => {
            cg.sync().await.unwrap();
        }
    }
}

/// Unhooked `git commit` → the watcher's diff-scoped sync makes the new symbol
/// searchable.