v2.0.5 nVidia nim & statusline fix

v2.0.5: NVIDIA NIM fixes, statusline live-update, config routing updates

- Fix NVIDIA MODEL_MAP: stepfun/step-3-7-flash -> stepfun-ai/step-3.7-flash (live API catalog)
- Fix NVIDIA base_url: add /chat/completions (was causing 404)
- Add NVIDIA model slug_overrides to config.yaml and openrouter.py KNOWN_SLUGS
- Rewrite manual_statusline_start.py: live-updating single-line display (2s refresh, \r overwrite)
- Update test_resolve_route.py for current routing config
- Update config.yaml routing to user's current setup