refactor: Move underlying_operand concept into operations namespace

Author: FrozenLemonTee

src/operations/operators.cppm

@@ -17,6 +17,13 @@ import mcpplibs.primitives.policy.handler;
 import mcpplibs.primitives.policy.impl;
 import mcpplibs.primitives.underlying.traits;
 
+namespace mcpplibs::primitives::operations {
+
+template <typename T>
+concept underlying_operand = underlying_type<std::remove_cvref_t<T>>;
+
+} // namespace mcpplibs::primitives::operations
+
 export namespace mcpplibs::primitives::operations {
 
 namespace details {
@@ -68,9 +75,6 @@ using primitive_dispatch_result_t = std::expected<meta::make_primitive_t<
         typename meta::traits<Lhs>::policies>,
     ErrorPayload>;
 
-template <typename T>
-concept underlying_operand = underlying_type<std::remove_cvref_t<T>>;
-
 template <meta::primitive_type Primitive, underlying_operand Underlying>
 using mixed_bridge_primitive_t = meta::make_primitive_t<
     std::remove_cvref_t<Underlying>, typename meta::traits<Primitive>::policies>;