MPPI planner + fence-line localization + scan obstacles

- Lightweight MPPI (200 trajectories, 15 steps, endpoint path_align)
- adaptive exploration (more random when stuck)
- fence-line Hough detection + geometric correction
- scan hit points marked at 255 immediately
- forward half-step pre-check for obstacle avoidance
- Ackermann constraint |wz| <= |vx|/min_turn_r
- XORshift RNG (stdlib broken on ARM)

CMakeLists.txt

@@ -0,0 +1,46 @@
+cmake_minimum_required(VERSION 3.8)
+project(car_nav_lite)
+
+if(NOT CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 17)
+endif()
+
+find_package(ament_cmake REQUIRED)
+find_package(rclcpp REQUIRED)
+find_package(std_msgs REQUIRED)
+find_package(geometry_msgs REQUIRED)
+find_package(nav_msgs REQUIRED)
+find_package(sensor_msgs REQUIRED)
+find_package(tf2 REQUIRED)
+find_package(tf2_ros REQUIRED)
+find_package(Eigen3 REQUIRED)
+find_package(OpenCV REQUIRED)
+
+set(INCLUDE_DIR include)
+
+add_executable(nav_lite_node
+  src/main.cpp
+  src/grid_map.cpp
+  src/localizer.cpp
+  src/global_planner.cpp
+  src/local_planner.cpp
+  src/bt_executor.cpp
+)
+
+target_include_directories(nav_lite_node PRIVATE
+  ${INCLUDE_DIR}
+  ${EIGEN3_INCLUDE_DIRS}
+)
+
+ament_target_dependencies(nav_lite_node
+  rclcpp std_msgs geometry_msgs nav_msgs sensor_msgs tf2 tf2_ros
+)
+target_link_libraries(nav_lite_node ${OpenCV_LIBS})
+
+add_executable(calib_check src/calib_check.cpp)
+target_include_directories(calib_check PRIVATE ${INCLUDE_DIR} ${EIGEN3_INCLUDE_DIRS})
+ament_target_dependencies(calib_check rclcpp geometry_msgs nav_msgs tf2 tf2_ros)
+install(TARGETS nav_lite_node calib_check DESTINATION lib/${PROJECT_NAME})
+install(DIRECTORY launch config maps DESTINATION share/${PROJECT_NAME})
+
+ament_package()