build(rhi): integrate SDL3 dependency with find_package and DLL auto-copy

- Add find_package(SDL3 REQUIRED CONFIG) to root CMakeLists.txt
- Link Caffeine library against SDL3::SDL3
- Add post-build SDL3 DLL copy for Windows test executable

Author: LyeZinho

CMakeLists.txt

@@ -12,19 +12,26 @@ if(CMAKE_BUILD_TYPE STREQUAL "Debug")
     add_compile_definitions(CF_DEBUG)
 endif()
 
+# ── SDL3 ────────────────────────────────────────────────────────
+find_package(SDL3 REQUIRED CONFIG)
+
 add_library(Caffeine
     src/core/Timer.cpp
     src/core/GameLoop.cpp
     src/input/InputManager.cpp
     src/debug/LogSystem.cpp
     src/debug/Profiler.cpp
+    src/rhi/RenderDevice.cpp
+    src/rhi/CommandBuffer.cpp
 )
 
 target_include_directories(Caffeine PUBLIC 
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
     $<INSTALL_INTERFACE:include>
 )
 
+target_link_libraries(Caffeine PUBLIC SDL3::SDL3)
+
 target_compile_features(Caffeine PUBLIC cxx_std_20)
 
 add_library(Caffeine::Core ALIAS Caffeine)

tests/CMakeLists.txt

@@ -9,6 +9,7 @@ add_executable(CaffeineTest
     test_gameloop.cpp
     test_input.cpp
     test_debug.cpp
+    test_rhi.cpp
 )
 
 target_link_libraries(CaffeineTest PRIVATE Caffeine)
@@ -20,4 +21,12 @@ else()
 endif()
 
 enable_testing()
-add_test(NAME CaffeineTest COMMAND CaffeineTest)
+add_test(NAME CaffeineTest COMMAND CaffeineTest)
+
+if(WIN32)
+    add_custom_command(TARGET CaffeineTest POST_BUILD
+        COMMAND ${CMAKE_COMMAND} -E copy_if_different
+            $<TARGET_FILE:SDL3::SDL3>
+            $<TARGET_FILE_DIR:CaffeineTest>
+    )
+endif()