Document uv package management and fix CI formatting failures

[Copilot]

README incorrectly documented uv pip install for adding dependencies and didn't clarify Hydra/W&B are optional. CI was failing on black formatting checks.

Changes

• Package installation: Updated README to use uv add which automatically updates pyproject.toml

  # Before: uv pip install package-name + manual pyproject.toml edit
  # After: uv add package-name
  uv add --dev package-name          # dev dependencies
  uv add "package-name>=1.0.0"       # version constraints
  uv add package1 package2 package3  # multiple packages

• Optional dependencies: Added explicit notes in Features and Running Experiments sections that Hydra and W&B can be removed from pyproject.toml if not needed

• CI fix: Split long pytest.raises() line in tests/test_example.py to comply with 79-character limit

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