Update C++ implementation to use Contract instead of Ensure

- Renamed C++ namespaces from Platform::Exceptions::Ensure to Platform::Exceptions::Contract
- Updated all C++ test files to use the new Contract namespace
- Maintained consistency between C# and C++ implementations

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: konard

cpp/Platform.Exceptions.Tests/ContractTests.cpp

@@ -0,0 +1,7 @@
+namespace Platform::Exceptions::Tests
+{
+    TEST(ContractTests, ArgumentNotNullContractTest)
+    {
+        EXPECT_THROW(Contract::Always::ArgumentNotNull(nullptr, "object"), std::invalid_argument);
+    };
+}

cpp/Platform.Exceptions.Tests/EnsuranceTests.cpp

@@ -1,6 +1,6 @@
 namespace Platform::Exceptions::Tests::Ignore
 {
-    TEST(IgnoredEnsuranceTests, EnsuranceIgnoredTest)
+    TEST(IgnoredContractTests, ContractIgnoredTest)
     {
         EXPECT_NO_THROW(Always::ArgumentNotNull(nullptr, "object"));
     };

…ptions.Tests/Ignore/EnsureExtensions.cpp …ions.Tests/Ignore/ContractExtensions.cppcpp/Platform.Exceptions.Tests/Ignore/EnsureExtensions.cpp renamed to cpp/Platform.Exceptions.Tests/Ignore/ContractExtensions.cpp cpp/Platform.Exceptions.Tests/Ignore/EnsureExtensions.cpp renamed to cpp/Platform.Exceptions.Tests/Ignore/ContractExtensions.cpp

@@ -1,4 +1,4 @@
-namespace Platform::Exceptions::Ensure::Always
+namespace Platform::Exceptions::Contract::Always
 {
     void ArgumentNotNull(auto argument, const std::string& argumentName, const std::string& message)
         requires std::is_pointer_v<decltype(argument)> || std::is_null_pointer_v<decltype(argument)>
@@ -47,7 +47,7 @@
     }
 }
 
-namespace Platform::Exceptions::Ensure::OnDebug
+namespace Platform::Exceptions::Contract::OnDebug
 {
 #ifdef NDEBUG
     #define NDEBUG_CONSTEVAL consteval