Optimize comparison of parsed versions

[ericmj]

Version.compare/2 converted parsed %Version{} values into two five-element tuples before comparing them. This adds a struct-to-struct clause that passes the precedence fields directly to the comparator, avoiding both tuple allocations. String and mixed operands retain parsing and validation through to_matchable/2, then call the same field comparator. Build metadata remains ignored.

Benchmarks used Elixir 1.21.0-dev, Erlang/OTP 29, macOS arm64, and one scheduler (+S 1:1). The benchmark baseline was bc7844c. Five runs produced 500 batch-average samples for individual comparisons and 150 complete-operation samples across six shuffled, one ascending, and one descending input order.

Timed boundary	Baseline median / p99	Updated median / p99	Median speedup
Early-core comparison	34.06 / 47.14 ns	19.40 / 24.44 ns	1.76x
Numeric-prerelease comparison	49.77 / 60.15 ns	32.65 / 40.10 ns	1.52x
Long-alphanumeric comparison	45.92 / 55.23 ns	29.61 / 35.01 ns	1.55x
Build-only difference	55.18 / 76.30 ns	39.38 / 46.36 ns	1.40x
1,000-digit core comparison	54.26 / 63.74 ns	37.85 / 44.28 ns	1.43x
Sort 895 parsed versions	369.50 / 589.58 us	258.25 / 404.08 us	1.43x
Sort 2,964 parsed versions	1.373 / 2.463 ms	1.019 / 1.217 ms	1.35x
Select maximum from 895 parsed versions	34.88 / 77.42 us	27.79 / 80.00 us	1.26x
Select maximum from 2,964 parsed versions	102.29 / 189.00 us	77.67 / 137.88 us	1.32x

Parsed sorting and maximum selection exclude parsing. Parsing strings once and then sorting improved by 1.09x at 895 versions and 1.06x at 2,964 versions, although the per-run median ranges overlapped. Sorting strings through the public comparator remained within run variation.

OTP tprof allocation profiling measured 12 heap words, or 96 bytes on this VM, per baseline parsed comparison and zero words after the change. The semantic oracle compared 38,416 ordered pairs, including arbitrary-size core and prerelease integers, mixed and prefix prerelease lists, stable releases, build ties, and long identifiers, with no mismatches.

make format and make test_stdlib TEST_FILES=version_test.exs pass with 43 tests.