chore(daemon): remove unused imports and dead placeholders

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/spaceshd/src/persist.rs

@@ -1,12 +1,8 @@
 use std::sync::Arc;
-use std::sync::atomic::{AtomicUsize, Ordering};
 use tokio::sync::mpsc;
 use tokio::time::{Duration, Instant};
 use crate::state_store::{PersistState, StateStore};
 
-/// Debounce window: coalesce a burst of dirty signals into one save.
-const DEBOUNCE: Duration = Duration::from_millis(500);
-
 /// A handle the registry uses to request a persist. `mark_dirty(state)` records
 /// the latest snapshot and (re)arms the debounce timer.
 #[derive(Clone)]
@@ -59,12 +55,10 @@ pub fn spawn(store: Arc<dyn StateStore>, debounce: Duration) -> Persister {
     Persister { tx }
 }
 
-#[allow(dead_code)]
-fn _unused(_c: &AtomicUsize) {}
-
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::sync::atomic::{AtomicUsize, Ordering};
     use std::sync::Mutex;
 
     struct CountingStore {