refactor(peer): split local library and operation UI events

Replace the `a9f9845` local-update dedup cache with explicit peer event
semantics. Local scans now emit `LocalLibraryChanged` when the library changes,
while operation mutations emit `ActiveOperationsChanged` from the mutation
path. Tauri keeps joining those facts into the existing `games-list-updated`
payload, so the frontend contract stays stable.

This removes the cache/invalidation coupling between scan emission and
operation state. The remaining forced local snapshot is explicit: accepted game
directory changes can refresh the UI for an equivalent new path without sending
a peer library delta.

Operation guard cleanup and liveness cancellation now publish the same active
operation snapshot as normal command-handler transitions. The peer CLI JSONL
events follow the same split with `local-library-changed` and
`active-operations-changed`.

Test Plan:
- `just fmt`
- `CARGO_BUILD_RUSTC_WRAPPER= just test`
- `CARGO_BUILD_RUSTC_WRAPPER= just clippy`
- `git diff --check`

Refs: CLEAN_CODE_PLAN_1.md

crates/lanspread-peer/src/services/local_monitor.rs

@@ -391,19 +391,15 @@ mod tests {
 
     async fn recv_local_update(
         rx: &mut mpsc::UnboundedReceiver<PeerEvent>,
-    ) -> (Vec<lanspread_db::db::Game>, Vec<crate::ActiveOperation>) {
+    ) -> Vec<lanspread_db::db::Game> {
         let event = tokio::time::timeout(Duration::from_secs(1), rx.recv())
             .await
             .expect("local update event should arrive")
             .expect("event channel should stay open");
-        let PeerEvent::LocalGamesUpdated {
-            games,
-            active_operations,
-        } = event
-        else {
-            panic!("expected LocalGamesUpdated");
+        let PeerEvent::LocalLibraryChanged { games } = event else {
+            panic!("expected LocalLibraryChanged");
         };
-        (games, active_operations)
+        games
     }
 
     #[test]
@@ -537,7 +533,7 @@ mod tests {
         ctx.task_tracker.wait().await;
 
         let mut update_count = 0;
-        while let Ok(Some(PeerEvent::LocalGamesUpdated { .. })) =
+        while let Ok(Some(PeerEvent::LocalLibraryChanged { .. })) =
             tokio::time::timeout(Duration::from_millis(50), rx.recv()).await
         {
             update_count += 1;
@@ -560,8 +556,7 @@ mod tests {
 
         run_fallback_scan(&ctx, &tx).await;
 
-        let (games, active_operations) = recv_local_update(&mut rx).await;
-        assert!(active_operations.is_empty());
+        let games = recv_local_update(&mut rx).await;
         let game = games
             .iter()
             .find(|game| game.id == "game")
@@ -585,9 +580,12 @@ mod tests {
 
         run_fallback_scan(&ctx, &tx).await;
 
-        let (games, active_operations) = recv_local_update(&mut rx).await;
-        assert!(games.is_empty());
-        assert!(active_operations.is_empty());
+        assert!(
+            tokio::time::timeout(Duration::from_millis(50), rx.recv())
+                .await
+                .is_err(),
+            "non-catalog scan should not emit a local library event"
+        );
         let library = ctx.local_library.read().await;
         assert!(library.games.is_empty());
         assert!(library.recent_deltas.is_empty());