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/mod_manager.go

@@ -60,8 +60,8 @@ func ListLocalMods(modsDir string) []ModInfo {
 			displayName = name[1:]
 		}
 		mods = append(mods, ModInfo{
-			ID:   displayName,
-			Name: name,
+			ID:     displayName,
+			Name:   name,
 			Source: "local",
 			Path:   p,
 			Size:   size,