fix: range exact/non-equal matches ignore build metadata

Build metadata does not affect precedence (SemVer 2.0.0 §10), so
the Eq and Neq constraints now use SemanticVersionComparer.Priority
instead of the structural == operator. This makes [1.2.3] match
1.2.3+build, consistent with precedence semantics.

Add a failing-then-passing test.

src/semver.tests/SemanticVersionRangeTests.cs

@@ -248,6 +248,15 @@ internal sealed class SemanticVersionRangeTests
 		await Assert.That(new string(destination[..charsWritten])).IsEqualTo("^1.2.3");
 	}
 
+	[Test]
+	public async Task I_can_match_exact_range_ignoring_build_metadata()
+	{
+		var range = SemanticVersionRange.Parse("[1.2.3]");
+
+		await Assert.That(range.Contains(SemanticVersion.Parse("1.2.3+build.7"))).IsTrue();
+		await Assert.That(range.Contains(SemanticVersion.Parse("1.2.4"))).IsFalse();
+	}
+
 	[Test]
 	public async Task I_fail_formatting_when_the_tentative_short_form_overflows()
 	{