refactor: drop openmmlab package deps from train/test workflows

[GeorgePearse]

Summary

• remove remaining runtime dependencies on mmcv, mmdet, and mmengine from active train/test entrypoints
• rewrite tools/train.py and tools/test.py to use visdet-native config/runner flows
• remove legacy tool scripts that depended on the old OpenMMLab stack (analysis/deployment/dataset conversion/misc/model converter scripts listed in this diff)
• remove broken duplicate helper scripts (scripts/test_presets_simple.py, scripts/test_yaml_simple.py)
• update related config/docs references:
  • coverage target mmdet -> visdet
  • release install snippet mmdet -> visdet
  • YAML config doc points to scripts/test_yaml_config.py
  • model-zoo generator emits visdet-based usage snippet and supports --output

Why

This repository should not require the external OpenMMLab packages for supported workflows. The key user-facing train/test entrypoints now run on visdet-native code only.

Validation

• uv run python -m py_compile tools/train.py tools/test.py scripts/generate_model_zoo.py visdet/engine/model/utils.py visdet/engine/utils/dl_utils/misc.py
• uv run python tools/train.py --help
• uv run python tools/test.py --help
• uv run pytest -v --tb=short
  • result: 77 passed, 45 skipped, 0 failed
• import scan (python files, excluding a codediff test fixture file):
  • no direct import/from mmcv|mmdet|mmengine remains

Notes

• tools/codediff/tests/test_parser.py still contains mmcv/mmengine import strings as fixture text for normalization tests; it does not import those packages at runtime.

[github-actions]

✅ Skylos Scan: No dead code or security issues detected.