fix(nixos): expose Pikachu paths to Valheim runtime

configs/nixos/hosts/pikachu/default.nix

@@ -7,6 +7,15 @@
 # pikachu — AZW ME Pro server.
 # Disk layout is in ./disk.nix.
 # `fileSystems` for the root disk are derived from it.
+let
+  valheimSteamRun = pkgs.steam-run.override {
+    extraBwrapArgs = [
+      "--bind"
+      "/pikachu"
+      "/pikachu"
+    ];
+  };
+in
 {
   imports = [
     ./hardware-configuration.nix
@@ -75,7 +84,7 @@
       installDir = "/pikachu/data/servers/valheim/main";
       workingDirectory = "/pikachu/data/servers/valheim/main";
       dataDirs = [ "/pikachu/media/games/servers/valheim/main" ];
-      packages = [ pkgs.steam-run ];
+      packages = [ valheimSteamRun ];
       environment = {
         SteamAppId = "892970";
         SERVER_PASSWORD = "foobarbaz";
@@ -84,7 +93,6 @@
         "${pkgs.bash}/bin/bash"
         "-c"
         ''
-          ${pkgs.coreutils}/bin/install -d -m 0770 /pikachu/media/games/servers/valheim/main
           export LD_LIBRARY_PATH="$PWD/linux64:$LD_LIBRARY_PATH"
           exec steam-run ./valheim_server.x86_64 \
             -nographics \