feat: add Wine Z: path prefix for Windows platform on Linux host

- Add winePath helper that prepends Z: when platform is windows on Linux
- Thread platform through buildModPath, buildAutoArgs, and Start()
- Apply Z: prefix to -config=, -mod=, -profiles=, and %command% binary paths
- Add tests for winePath, buildAutoArgs, and buildModPath with platform param
- Fix formatting across services package with gofmt
- Include all prior bug fixes from this branch

backend/internal/services/scheduler.go

@@ -63,7 +63,7 @@ func (s *Scheduler) runScheduledUpdate() {
 		return
 	}
 
-	if sett.SteamUser != "" && sett.SteamUser != "anonymous" {
+	if sett.SteamUser != "" {
 		log.Print("scheduler: running gameserver update")
 		if err := s.steamcmd.UpdateGame(sett.SteamBranch, sett.SteamUser); err != nil {
 			log.Printf("scheduler: game update failed: %v", err)