move the shared TOML helpers into the utility namespace to avoid name collisions

src/lib/config/TomlHelpers.h

@@ -13,6 +13,13 @@
 // Shared TOML-parsing helpers used by two or more ConfigLoader per-domain
 // loaders. Helpers used by exactly one domain stay local to that domain's
 // .cpp file instead.
+//
+// Namespaced because the names are generic: VisualsLoader.cpp and
+// BalancingConfig.cpp each have their own same-named helpers in anonymous
+// namespaces, and unqualified globals here would form an overload set with
+// them the moment either file includes this header.
+namespace utility
+{
 
 // --- Error helpers ----------------------------------------------------------
 
@@ -59,3 +66,5 @@ std::vector<RecipeIngredient> parseIngredients(const toml::array& arr,
                                                const std::string& path);
 
 toml::table parseFile(const std::string& path, const std::string& file);
+
+}  // namespace utility