v1.0.0

release: v1.0.0 — production hardening, CI/CD, and rigor fixes

Production readiness:
- Bump version to 1.0.0 (Cargo, pyproject, __version__, tests)
- Add LICENSE (MIT), SECURITY.md, CHANGELOG.md, Makefile, ruff.toml
- Mark Development Status 5 - Production/Stable; add project URLs
- Harden CI: Rust/Python lint jobs, fmt+clippy, ruff, expanded test matrix (3.10-3.13)
- Reformat entire Rust codebase with rustfmt; fix clippy errors
- Auto-fix ruff (UP031, B905, E741, import sorting)

Correctness fixes:
- None/newaxis setitem no longer panics (a[None, 0] = 9)
- Scalar division keeps reciprocal rounding error in the radius
- maximum/minimum propagate NaN/empty intervals