feat: add Unity color and check target

Enable UNITY_OUTPUT_COLOR and UNITY_INCLUDE_PRINT_FORMATTED via
compile definitions on the unity target so colors propagate to all
test suites automatically.

Add a 'check' custom target that builds all suites and runs CTest
with --output-on-failure and USES_TERMINAL, keeping ANSI colors
alive through Ninja's buffering.

deps/FindUnity.cmake

@@ -55,4 +55,11 @@ if (Unity_INCLUDE_DIR AND TARGET unity)
     )
 endif()
 
+if (TARGET unity)
+    target_compile_definitions(unity PUBLIC
+        UNITY_OUTPUT_COLOR
+        UNITY_INCLUDE_PRINT_FORMATTED
+    )
+endif()
+
 set(UNITY_LICENSE_FILE "${unity_SOURCE_DIR}/LICENSE.txt" CACHE FILEPATH "Path to Unity license file")