Feat: adds minimal GitHub actions

[carshadi]

Summary

Replaces the stale CircleCI setup with GitHub Actions workflows for CI and release versioning. CI now uses uv with a committed uv.lock for deterministic dependency resolution, and merged PRs to main trigger the shared AllenNeuralDynamics uv release workflow to bump, commit, and tag versions.

Changes

• Added .github/workflows/ci.yml.
• Added Python test matrix for 3.9, 3.10, 3.11, 3.12, and 3.13.
• Runs tests with:

  uv run --frozen --extra test python -m pytest

• Adds a build job that runs:

  uv build

• Adds a wheel-content check to ensure the top-level tests/ package is not included in the built wheel.
• Added .github/workflows/release.yml.
• Release workflow runs when a PR is merged into main.
• Release workflow delegates version bumping/tagging to:

  AllenNeuralDynamics/.github/.github/workflows/release-bump-version-uv.yml@main

• The shared release workflow updates pyproject.toml and uv.lock, commits the version bump, and pushes a v<version> tag.
• Added README release-maintenance notes documenting the shared release workflow behavior.
• Commits uv.lock so CI installs are reproducible.
• Updates .gitignore so GitHub workflow files can be tracked and .pytest_cache/ is ignored.
• Removes .circleci/config.yml.

Why CircleCI Was Removed

The existing CircleCI workflow was stale and no longer matched the project setup. It attempted to install dependencies from requirements.txt, but this repo now uses pyproject.toml and uv, and there is no requirements.txt present.

Removing CircleCI makes GitHub Actions the single CI source of truth and aligns the workflows with the current package metadata and lockfile-based dependency management.

Validation

Local checks run:

uv run --frozen --extra test python -m pytest
uv build
uv version --bump patch --dry-run --output-format json
git diff --check

Result:

29 passed, 1 warning
uv build passed
dry-run patch bump reported 0.1.1
git diff --check passed

The warning is from the existing pandas delim_whitespace usage and is not introduced by this PR.