Add packagename.Normalize as the PEP 503 entry point (#68)

* Add packagename.Normalize as the PEP 503 entry point (#25)

* pr feedback

* pr feedback: using strings.Builder

Add Metadata 2.5/2.6 support, fix License-File multiplicity (#64)

chore(release): date 0.10.0 (#57)

Releases wheelname.ParseTags (#56) so the PyPI manifest producer can consume it; rstudio/package-manager#20776 is blocked on this tag existing.

Additive only; Parse's behaviour is unchanged. Minor bump while major is 0.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

v0.7.0

Adds version.ReleaseKey: a version's position in PEP 440's release order --
its epoch and its trailing-zero-stripped release segments, ignoring the
pre/post/dev/local suffix -- derived from the parsed fields rather than by
rendering the version back to text.

16 ns and no allocation against 220 ns and 10 allocations for the
BaseVersion() render-and-split it replaces. Pinned to pypa/packaging 26.2's
own release key by a frozen fixture, and exact at every magnitude.

v0.6.0

Packed integer comparison key for version.Version: 97.26% of production
PyPI versions compare via a few integer operations with zero
allocations; 2.1-5.2x faster warm resolutions end to end. Ordering
pinned to pypa/packaging 26.2 by frozen ranked fixtures in CI. A parsed
Version is now safe to share across goroutines.

v0.5.0

Breaking. Fixes a padding defect shipped in v0.4.0: the zero-padding loops
appended ceil(gap/2) zeros instead of gap, because the loop bound shrank as the
slice grew. Measured against pypa/packaging 26.2 over an 82-row oracle sweeping
gaps of 1-4 in both directions: v0.4.0 diverged on 30 of 82 cases, this release
on 0. Notably !=7.0.0.* matched 7, which the reference excludes.

v0.4.0 also introduced a regression this fixes: ==0.0.0.* matched 1!1.0 because
versionSplit did not prepend the epoch. v0.4.0's notes wrongly described those
cases as a pre-existing divergence merely exposed.

Also: the public Specifier/Specifiers query API and marker environment helpers;
the ported test_specifiers.py conformance tables (2,105 subtests) and the six
divergences they surfaced; and tags/ gaining free-threaded and abi3t ABIs,
distro libc baselines, pre-11 macOS, PyPy ABI, the cross-major manylinux walk,
and the pre-3.8 m/u abiflags fix.

v0.4.0

Breaking: a comma is now required between version constraints in a specifier set.
Measured over the production PyPI snapshot (2,804,136 distinct requirement strings):
21 newly rejected, 0 newly accepted. Zero change over real CRAN data for the R path.