[M5+] resolve_version + cmd_add lockfile pin

tests/cmd_remove.cpp

@@ -13,6 +13,13 @@ namespace manifest = cargoxx::manifest;
 
 namespace {
 
+// Disable the network resolver chains in cmd_add (which we use as a
+// fixture-builder). Per-version-resolution tests live elsewhere.
+struct DisableAutoResolveScope {
+    DisableAutoResolveScope() { setenv("CARGOXX_NO_AUTORESOLVE", "1", 1); }
+};
+const DisableAutoResolveScope autoresolve_disabled_;
+
 auto fresh_dir() -> std::filesystem::path {
     auto d = std::filesystem::temp_directory_path() /
              std::format("cargoxx-remove-test-{}", std::random_device{}());