build: configure BuildInfo generation via CMake

.clangd

@@ -1,2 +1,7 @@
 CompileFlags:
   CompilationDatabase: build
+
+If:
+  PathMatch: .*\.in$
+Diagnostics:
+  Suppress: "*"

core/BuildInfo.hpp.in

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <string_view>
+
+namespace retroforge::core {
+
+class BuildInfo {
+  public:
+    static constexpr int major = @PROJECT_VERSION_MAJOR@;
+    static constexpr int minor = @PROJECT_VERSION_MINOR@;
+    static constexpr int patch = @PROJECT_VERSION_PATCH@;
+
+    static constexpr std::string_view version_string() { return "@PROJECT_VERSION@"; }
+};
+
+} // namespace retroforge::core

core/CMakeLists.txt

@@ -15,4 +15,14 @@ target_include_directories(retroforge_core PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}/src
 )
 
+configure_file(
+    ${CMAKE_CURRENT_SOURCE_DIR}/BuildInfo.hpp.in
+    ${CMAKE_BINARY_DIR}/generated/BuildInfo.hpp
+    @ONLY
+)
+
+target_include_directories(retroforge_core PUBLIC
+    ${CMAKE_BINARY_DIR}/generated
+)
+
 target_compile_features(retroforge_core PUBLIC cxx_std_20)