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-tauri-deno-ts/src/hooks/useGameActions.ts

@@ -1,5 +1,6 @@
 import { useCallback } from 'react';
 import { invoke } from '@tauri-apps/api/core';
+import { ask } from '@tauri-apps/plugin-dialog';
 
 import { type UseGamesResult } from './useGames';
 import { type UISettings } from './useSettings';
@@ -69,6 +70,14 @@ export const useGameActions = (
 
     const update = useCallback(async (id: string) => {
         try {
+            const game = games.games.find(item => item.id === id);
+            if (game && game.active_outbound_transfers && game.active_outbound_transfers > 0) {
+                const confirmed = await ask(
+                    `Peers are currently downloading this game from you. Updating will abort their downloads. Do you want to proceed?`,
+                    { title: 'Active Transfers in Progress', kind: 'warning' }
+                );
+                if (!confirmed) return;
+            }
             const success = await invoke<boolean>('update_game', {
                 id,
                 language: settings.language,
@@ -90,11 +99,19 @@ export const useGameActions = (
 
     const removeDownload = useCallback(async (id: string) => {
         try {
+            const game = games.games.find(item => item.id === id);
+            if (game && game.active_outbound_transfers && game.active_outbound_transfers > 0) {
+                const confirmed = await ask(
+                    `Peers are currently downloading this game from you. Removing game files will abort their downloads. Do you want to proceed?`,
+                    { title: 'Active Transfers in Progress', kind: 'warning' }
+                );
+                if (!confirmed) return;
+            }
             await invoke('remove_downloaded_game', { id });
         } catch (err) {
             console.error('remove_downloaded_game failed:', err);
         }
-    }, []);
+    }, [games]);
 
     const cancelDownload = useCallback(async (id: string) => {
         try {