refactor: Move policy to a separate submodule

Author: FrozenLemonTee

src/traits/policy.cppm src/policy/impl.cppmsrc/traits/policy.cppm renamed to src/policy/impl.cppm

@@ -1,16 +1,10 @@
 module;
 
-export module mcpplibs.primitives.traits.policy;
+export module mcpplibs.primitives.policy.impl;
 
-export namespace mcpplibs::primitives::policy {
-
-enum class category { value, type, error, concurrency };
+import mcpplibs.primitives.policy.traits;
 
-template <typename P> struct traits {
-  using policy_type = void;
-  static constexpr bool enabled = false;
-  static constexpr auto kind = static_cast<category>(-1);
-};
+export namespace mcpplibs::primitives::policy {
 
 struct checked_value {};
 struct unchecked_value {};

src/policy/policy.cppm

@@ -0,0 +1,7 @@
+module;
+
+export module mcpplibs.primitives.policy;
+
+// Entry module for policy: export traits and impl submodules.
+export import mcpplibs.primitives.policy.traits;
+export import mcpplibs.primitives.policy.impl;

src/policy/traits.cppm

@@ -0,0 +1,18 @@
+module;
+
+export module mcpplibs.primitives.policy.traits;
+
+// Primary template and category enum for policy traits. Concrete policy tags
+// and specializations live in the implementation submodule.
+
+export namespace mcpplibs::primitives::policy {
+
+enum class category { value, type, error, concurrency };
+
+template <typename P> struct traits {
+  using policy_type = void;
+  static constexpr bool enabled = false;
+  static constexpr auto kind = static_cast<category>(-1);
+};
+
+} // namespace mcpplibs::primitives::policy