Refine packaging CI and metric summaries

[ftshijt]

Summary

This PR refines the repository maintenance surface and makes the default developer path lighter.

Changes

• Move package metadata and dependency declarations into pyproject.toml
• Keep setup.py as a small setuptools compatibility shim
• Split heavy metric/model dependencies into optional extras: audio, text, ml, external, dev, and test
• Remove the static versa/metrics.py metric-output registry
• Infer numeric summaries directly from scorer output values
• Harden CLI behavior:
  • use real boolean flags for --use_gpu
  • check CUDA availability before selecting a device
  • use yaml.safe_load
• Update CI to be check-only and dependency-light
• Update README, CI docs, and contribution docs for the new packaging and metric-registration flow
• Add focused tests for summary inference and explicit compute_parallel behavior

Motivation

The previous default install pulled many heavyweight optional dependencies, including model/toolkit packages that are not required for every workflow. CI also depended on that broad install surface and auto-committed formatting changes, which made maintenance noisier.

This change makes the base package easier to install, keeps optional metric backends explicit, and removes the need to manually maintain a separate metric-output classification list.

Validation

• conda run -n versa-dev python -m pytest -q test/test_metrics/test_definition.py
• conda run -n versa-dev python -m compileall -q versa test scripts setup.py
• git ls-files -- '*.py' | grep -v '^versa/metrics.py$' | xargs conda run -n versa-dev python -m black --check
• conda run -n versa-dev python -m flake8 versa scripts test setup.py --count --select=E9,F63,F7,F82 --show-source --statistics
• git diff --check --cached
• conda run -n versa-dev python -m pip install -e . --dry-run --no-build-isolation