Initial commit: FAST-LIO ROS2 workspace for duru_lio

Clean up config/rviz assets for MID360S-only deployment and split
run scripts by role (headless LIO via ssh, rviz-only on the local
monitor, and combined run) so mapping.launch.py no longer needs
config_file passed explicitly.

.gitmodules

@@ -0,0 +1,4 @@
+[submodule "include/ikd-Tree"]
+	path = include/ikd-Tree
+	url = https://github.com/hku-mars/ikd-Tree.git
+	branch = fast_lio