perf(mapping): reduce Jetson memory usage in occupancy SDF generation

[junlinp]

Summary

• refactor occupancy SDF generation in build_map_node to use SciPy EDT only
• remove legacy numba min-distance SDF path
• fix build_map_node syntax issue in occupancy logging
• add true 3D SDF visualization in poi_editor
• add 3D SDF search-region overlay for the map_node threshold (sdf < 0.2m)

Files

• tinynav/core/build_map_node.py
• tool/poi_editor.py

Notes

• local-only changes intentionally not included in this PR: scripts/run_rosbag_build_map.sh, tests/test_generate_occupancy_map_beilun.py

[github-actions]

cloc	github.com/AlDanial/cloc v 2.04 T=0.16 s (245.5 files/s, 36403.3 lines/s)

Language	files	blank	comment	code
Python	12	581	257	3231
Markdown	4	155	6	426
C++	4	60	38	409
Bourne Shell	14	32	9	242
Dockerfile	1	30	29	191
JSON	2	8	0	58
TOML	1	4	0	57
make	1	18	15	55
CMake	1	4	0	17
--------	--------	--------	--------	--------
SUM:	40	892	354	4686