feat(peer): remove downloaded game files safely

Downloaded but uninstalled games can still occupy significant disk space. Add a
separate removal path for that state instead of overloading uninstall, which is
reserved for deleting only `local/` installs.

The peer runtime now exposes `RemoveDownloadedGame` with matching lifecycle
and active-operation events. The filesystem delete is intentionally strict: the
id must be a catalog game and a single path component, the target must be a
direct child of the configured game directory, the root must not be a symlink,
it must have a regular root-level `version.ini`, and it must not contain
`local/`, `.local.installing/`, or `.local.backup/`. Only then do we recursively
remove the game root.

The Tauri bridge exposes this as `remove_downloaded_game`, the frontend shows a
matching danger action only for downloaded-but-uninstalled games, and a
confirmation dialog warns that re-downloading can take a long time.

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

Refs: user redesign nitpick about removing downloaded uninstalled games

crates/lanspread-tauri-deno-ts/src-tauri/src/lib.rs

@@ -52,6 +52,7 @@ enum UiOperationKind {
     Installing,
     Updating,
     Uninstalling,
+    RemovingDownload,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, serde::Serialize)]
@@ -230,6 +231,54 @@ async fn uninstall_game(
     }
 }
 
+#[tauri::command]
+async fn remove_downloaded_game(
+    id: String,
+    state: tauri::State<'_, LanSpreadState>,
+) -> tauri::Result<bool> {
+    if state
+        .inner()
+        .active_operations
+        .read()
+        .await
+        .contains_key(&id)
+    {
+        log::warn!("Game already has an active operation: {id}");
+        return Ok(false);
+    }
+
+    let Some((downloaded, installed)) = state
+        .inner()
+        .games
+        .read()
+        .await
+        .get_game_by_id(&id)
+        .map(|game| (game.downloaded, game.installed))
+    else {
+        log::warn!("Ignoring downloaded-file removal for unknown game: {id}");
+        return Ok(false);
+    };
+    if !downloaded || installed {
+        log::warn!(
+            "Ignoring downloaded-file removal for {id}: downloaded={downloaded}, installed={installed}"
+        );
+        return Ok(false);
+    }
+
+    let peer_ctrl_arc = state.inner().peer_ctrl.clone();
+    let peer_ctrl = peer_ctrl_arc.read().await.clone();
+    if let Some(peer_ctrl) = peer_ctrl {
+        if let Err(e) = peer_ctrl.send(PeerCommand::RemoveDownloadedGame { id }) {
+            log::error!("Failed to send message to peer: {e:?}");
+            return Ok(false);
+        }
+        Ok(true)
+    } else {
+        log::warn!("Peer system not initialized yet");
+        Ok(false)
+    }
+}
+
 #[tauri::command]
 async fn get_peer_count(state: tauri::State<'_, LanSpreadState>) -> tauri::Result<usize> {
     let peer_ctrl_arc = state.inner().peer_ctrl.clone();
@@ -505,6 +554,7 @@ fn ui_operation_from_peer(operation: ActiveOperationKind) -> UiOperationKind {
         ActiveOperationKind::Installing => UiOperationKind::Installing,
         ActiveOperationKind::Updating => UiOperationKind::Updating,
         ActiveOperationKind::Uninstalling => UiOperationKind::Uninstalling,
+        ActiveOperationKind::RemovingDownload => UiOperationKind::RemovingDownload,
     }
 }
 
@@ -1064,6 +1114,33 @@ async fn handle_peer_event(app_handle: &AppHandle, event: PeerEvent) {
                 "PeerEvent::UninstallGameFailed",
             );
         }
+        PeerEvent::RemoveDownloadedGameBegin { id } => {
+            log::info!("PeerEvent::RemoveDownloadedGameBegin received for {id}");
+            emit_game_id_event(
+                app_handle,
+                "game-remove-download-begin",
+                &id,
+                "PeerEvent::RemoveDownloadedGameBegin",
+            );
+        }
+        PeerEvent::RemoveDownloadedGameFinished { id } => {
+            log::info!("PeerEvent::RemoveDownloadedGameFinished received for {id}");
+            emit_game_id_event(
+                app_handle,
+                "game-remove-download-finished",
+                &id,
+                "PeerEvent::RemoveDownloadedGameFinished",
+            );
+        }
+        PeerEvent::RemoveDownloadedGameFailed { id } => {
+            log::warn!("PeerEvent::RemoveDownloadedGameFailed received for {id}");
+            emit_game_id_event(
+                app_handle,
+                "game-remove-download-failed",
+                &id,
+                "PeerEvent::RemoveDownloadedGameFailed",
+            );
+        }
         PeerEvent::PeerConnected(addr) => {
             log::info!("Peer connected: {addr}");
             emit_peer_addr_event(app_handle, "peer-connected", addr);
@@ -1315,6 +1392,7 @@ pub fn run() {
             update_game_directory,
             update_game,
             uninstall_game,
+            remove_downloaded_game,
             get_peer_count,
             get_game_thumbnail,
             get_unpack_logs