sitl: add Gazebo plant and smoke harness

tools/sitl/CMakeLists.txt

@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 3.22 FATAL_ERROR)
+project(kaptan_sitl LANGUAGES CXX)
+
+# Gazebo Jetty deliberately supplies unversioned CMake package targets. The
+# image installs only the Jetty (gz-sim 10) development ABI, so an accidental
+# build against another Gazebo major fails at configuration time.
+find_package(gz-cmake REQUIRED)
+gz_find_package(gz-sim REQUIRED)
+
+add_library(kaptan_sitl_quad SHARED src/kaptan_sitl_quad.cc)
+target_compile_features(kaptan_sitl_quad PRIVATE cxx_std_20)
+target_compile_options(kaptan_sitl_quad PRIVATE -Wall -Wextra -Wpedantic -Werror)
+target_link_libraries(kaptan_sitl_quad PRIVATE gz-sim::gz-sim)