Function run_watcher 

pub async fn run_watcher(
    repo_root: PathBuf,
    shared: SharedIndex,
    watcher_info: Arc<Mutex<WatcherInfo>>,
)

Main watcher supervision loop. Spawned as a background tokio task by main.rs.

Lifecycle:

1. Set state to Active
2. Loop: start_watcher → process events → restart on error with 1s backoff
3. After 3 consecutive failures: set state to Degraded and stop