feat(peer): coordinate outbound transfers with local game mutations

Updating or removing a local game rewrites its on-disk files. Peers that
were mid-download of that game would keep streaming bytes from files that
are being deleted or replaced, handing them a corrupt or stale copy.
There was also no authoritative notion of which game version a peer
should serve or accept, so a peer could serve whatever happened to be on
disk and downloaders could aggregate files from peers running mismatched
versions.

This introduces a reader-writer coordination scheme between outbound file
transfers (readers) and local mutation operations (writers), and gates
both serving and downloading on an authoritative game catalog version.

Reader-writer coordination:
- Track active outbound transfers per game in a shared `OutboundTransfers`
  map of (id, CancellationToken), threaded through `Ctx`/`PeerCtx` and
  registered by a `TransferGuard` in the stream service. The guard is
  registered *before* the serve-eligibility check to close a TOCTOU window
  where a writer could miss an in-flight reader.
- `stream_file_bytes` now honors a cancellation token at every await point
  (file read, network send, stream close) via `tokio::select!`, so a
  transfer aborts promptly instead of hanging on a stalled receiver.
- `begin_operation` marks a game active first, then cancels its outbound
  transfers and waits for the count to reach zero before any
  Updating/RemovingDownload work touches the filesystem.
- Active games are now hidden from library snapshots entirely while an
  operation is in flight, instead of freezing their last announced state,
  so peers stop discovering a game that is being mutated.

Authoritative version catalog:
- Replace the `HashSet<String>` catalog with `GameCatalog`, mapping each
  game id to its expected version (from the bundled game.db / ETI data).
- Serving requires the local `version.ini` to match the catalog version
  (`local_download_matches_catalog`); peer selection, file aggregation,
  and majority size validation all filter on the expected version
  (`peers_with_expected_version`, `aggregated_game_files`, and friends).

User-visible changes:
- The GUI shows confirmation dialogs before Update and Remove, and
  surfaces a sharing-status indicator on game cards and the detail modal.
- A new `OutboundTransferCountChanged` event lets the UI reflect live
  outbound transfer activity.

Test Plan:
- just test
- just frontend-test
- just clippy

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

@@ -2,6 +2,7 @@
 
 use std::{collections::HashMap, sync::Arc, time::Duration};
 
+use lanspread_db::db::GameCatalog;
 use tokio::sync::{RwLock, mpsc::UnboundedSender};
 use tokio_util::{sync::CancellationToken, task::TaskTracker};
 
@@ -18,6 +19,7 @@ use crate::{
 pub async fn run_ping_service(
     tx_notify_ui: UnboundedSender<PeerEvent>,
     peer_game_db: Arc<RwLock<PeerGameDB>>,
+    catalog: Arc<RwLock<GameCatalog>>,
     active_operations: Arc<RwLock<HashMap<String, OperationKind>>>,
     active_downloads: Arc<RwLock<HashMap<String, CancellationToken>>>,
     shutdown: CancellationToken,
@@ -40,6 +42,7 @@ pub async fn run_ping_service(
 
         ping_idle_peers(
             &peer_game_db,
+            &catalog,
             &active_operations,
             &active_downloads,
             &tx_notify_ui,
@@ -50,6 +53,7 @@ pub async fn run_ping_service(
 
         prune_stale_peers(
             &peer_game_db,
+            &catalog,
             &active_operations,
             &active_downloads,
             &tx_notify_ui,
@@ -60,6 +64,7 @@ pub async fn run_ping_service(
 
 async fn ping_idle_peers(
     peer_game_db: &Arc<RwLock<PeerGameDB>>,
+    catalog: &Arc<RwLock<GameCatalog>>,
     active_operations: &Arc<RwLock<HashMap<String, OperationKind>>>,
     active_downloads: &Arc<RwLock<HashMap<String, CancellationToken>>>,
     tx_notify_ui: &UnboundedSender<PeerEvent>,
@@ -75,6 +80,7 @@ async fn ping_idle_peers(
 
         let tx_notify_ui = tx_notify_ui.clone();
         let peer_game_db = peer_game_db.clone();
+        let catalog = catalog.clone();
         let active_operations = active_operations.clone();
         let active_downloads = active_downloads.clone();
         let shutdown = shutdown.clone();
@@ -93,6 +99,7 @@ async fn ping_idle_peers(
                     log::warn!("Peer {peer_addr} failed ping check");
                     remove_peer_and_refresh(
                         &peer_game_db,
+                        &catalog,
                         &active_operations,
                         &active_downloads,
                         &tx_notify_ui,
@@ -105,6 +112,7 @@ async fn ping_idle_peers(
                     log::error!("Failed to ping peer {peer_addr}: {err}");
                     remove_peer_and_refresh(
                         &peer_game_db,
+                        &catalog,
                         &active_operations,
                         &active_downloads,
                         &tx_notify_ui,
@@ -120,6 +128,7 @@ async fn ping_idle_peers(
 
 async fn prune_stale_peers(
     peer_game_db: &Arc<RwLock<PeerGameDB>>,
+    catalog: &Arc<RwLock<GameCatalog>>,
     active_operations: &Arc<RwLock<HashMap<String, OperationKind>>>,
     active_downloads: &Arc<RwLock<HashMap<String, CancellationToken>>>,
     tx_notify_ui: &UnboundedSender<PeerEvent>,
@@ -137,7 +146,7 @@ async fn prune_stale_peers(
     }
 
     if removed_any {
-        events::emit_peer_game_list(peer_game_db, tx_notify_ui).await;
+        events::emit_peer_game_list(peer_game_db, catalog, tx_notify_ui).await;
         handle_active_downloads_without_peers(
             peer_game_db,
             active_operations,
@@ -150,6 +159,7 @@ async fn prune_stale_peers(
 
 async fn remove_peer_and_refresh(
     peer_game_db: &Arc<RwLock<PeerGameDB>>,
+    catalog: &Arc<RwLock<GameCatalog>>,
     active_operations: &Arc<RwLock<HashMap<String, OperationKind>>>,
     active_downloads: &Arc<RwLock<HashMap<String, CancellationToken>>>,
     tx_notify_ui: &UnboundedSender<PeerEvent>,
@@ -157,7 +167,7 @@ async fn remove_peer_and_refresh(
     log_label: &str,
 ) {
     if remove_peer(peer_game_db, tx_notify_ui, peer_id, log_label).await {
-        events::emit_peer_game_list(peer_game_db, tx_notify_ui).await;
+        events::emit_peer_game_list(peer_game_db, catalog, tx_notify_ui).await;
         handle_active_downloads_without_peers(
             peer_game_db,
             active_operations,