feat(map): create POIs from bag marks

[xiaolefang-dm]

Summary

• Add a bag-time POI mark API for recording named POI timestamps during mapping bag capture.
• Add a Map tab Set POI button that prompts for a POI name while recording.
• Generate pois.json automatically after map build by matching POI marks to built map poses.

Details

POI marks are stored with the recorded bag as poi_marks.json. During map build, the backend reads these marks and maps each timestamp to the nearest available map pose. If continuous odometry is available, it uses it to refine the marked pose relative to the nearest optimized keyframe.

If no POI marks are available, the existing fallback behavior is preserved: create a default home POI at [0, 0, 0].

Test

• python3 -m py_compile app/backend/node_manager.py app/backend/routers/bag.py tests/test_backend.py
• git diff --check
• Deployed to test nano on branch xiaole/map-poi-marks
• Built frontend in container with flutter build web
• Restarted tinynav-dev and started /tinynav/scripts/start_app.sh
• Verified /device/status returns poiMarkCount
• Verified /bag/poi-marks returns 409 when not recording

[github-actions]

cloc	github.com/AlDanial/cloc v 2.04 T=0.18 s (233.3 files/s, 37281.4 lines/s)

Language	files	blank	comment	code
Python	13	678	305	3816
Markdown	4	155	6	426
C++	4	60	38	409
Bourne Shell	15	41	9	272
Dockerfile	1	31	32	204
JSON	2	8	0	58
TOML	1	4	0	58
make	1	18	15	49
CMake	1	4	0	17
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SUM:	42	999	405	5309