feat(threat-assessment): implement naval threat analysis with GPT-4o\n\n- Rename utils/gpt_distance.py to utils/gpt_reasoning.py and update logic for 15 naval threat features\n- Add Pydantic schemas for NavalThreatAssessment in utils/schemas.py\n- Update backend (app.py, inference.py) to use new threat estimation and pass full metadata\n- refactor(frontend): render threat level badges and detailed feature table in UI

Show first frame radar when processed image appears

Add military-style radar with helicopter demo mode

Refine overlays: Hide on first frame and remove speed from labels

feat: Implement depth-based distance estimation and frontend integration

feat: Radar historic traces and fix DETR crash

feat: Real-time radar directionality via track sync

feat: Continuous object tracking, speed estimation, and overlay syncing

Refactor frontend into modular ES modules in frontend/ folder