refactor: Using auto

Author: FrozenLemonTee

src/traits/policy.cppm

@@ -1,5 +1,4 @@
 module;
-#include <type_traits>
 
 export module mcpplibs.primitives.traits.policy;
 
@@ -10,7 +9,7 @@ enum class category { value, type, error, concurrency };
 template <typename P> struct traits {
   using policy_type = void;
   static constexpr bool enabled = false;
-  static constexpr category kind = static_cast<category>(-1);
+  static constexpr auto kind = static_cast<category>(-1);
 };
 
 struct checked_value {};
@@ -31,67 +30,67 @@ struct atomic {};
 template <> struct traits<checked_value> {
   using policy_type = checked_value;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::value;
+  static constexpr auto kind = category::value;
 };
 
 template <> struct traits<unchecked_value> {
   using policy_type = unchecked_value;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::value;
+  static constexpr auto kind = category::value;
 };
 
 template <> struct traits<saturating_value> {
   using policy_type = saturating_value;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::value;
+  static constexpr auto kind = category::value;
 };
 
 template <> struct traits<strict_type> {
   using policy_type = strict_type;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::type;
+  static constexpr auto kind = category::type;
 };
 
 template <> struct traits<category_compatible_type> {
   using policy_type = category_compatible_type;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::type;
+  static constexpr auto kind = category::type;
 };
 
 template <> struct traits<transparent_type> {
   using policy_type = transparent_type;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::type;
+  static constexpr auto kind = category::type;
 };
 
 template <> struct traits<throw_error> {
   using policy_type = throw_error;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::error;
+  static constexpr auto kind = category::error;
 };
 
 template <> struct traits<expected_error> {
   using policy_type = expected_error;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::error;
+  static constexpr auto kind = category::error;
 };
 
 template <> struct traits<terminate_error> {
   using policy_type = terminate_error;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::error;
+  static constexpr auto kind = category::error;
 };
 
 template <> struct traits<single_thread> {
   using policy_type = single_thread;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::concurrency;
+  static constexpr auto kind = category::concurrency;
 };
 
 template <> struct traits<atomic> {
   using policy_type = atomic;
   static constexpr bool enabled = true;
-  static constexpr category kind = category::concurrency;
+  static constexpr auto kind = category::concurrency;
 };
 
 template <typename P>