feat: comprehensive multi-track evaluation script + research log updates
- multitrack_eval.py: tests all 3 top models against all 11 DonkeyCar tracks
- Automatic track switching via exit_scene → reconnect
- 11 tracks: generated_road, generated_track, mountain, warehouse, AVC,
mini_monaco, warren, robo_racing, waveshare, thunderhill, circuit_launch
- Records: reward, steps, oscillation, CTE distribution, drove_far flag
- Saves to outerloop-results/multitrack_results.jsonl
- Prints comparison table at the end
- RESEARCH_LOG.md: exit_scene fix documented, Phase 3 begun
- IMPLEMENTATION_PLAN.md: Wave 3 streams defined
Agent: pi/claude-sonnet
Tests: 53/53 passing
Tests-Added: 0
TypeScript: N/A