Fix C# constructor alias arity resolution

[Widthdom]

Summary

• Preserve the canonical C# type identity and qualifier when a constructor is invoked through a using alias.
• Persist and consume the lexical constructor token span so simple positional invocation arity can isolate one-, two-, and three-parameter constructor families.
• Keep named arguments, optional/default or params families, binding-sensitive primary/explicit families, raw/interpolated expressions, ambiguous angle syntax, malformed calls, and invalid persisted spans conservative.
• Refresh unchanged C# files by advancing the extractor contract version.

Validation

• dotnet restore CodeIndex.sln
• dotnet format CodeIndex.sln --verify-no-changes --no-restore
• dotnet build CodeIndex.sln -c Release --no-restore — 0 warnings, 0 errors
• Focused Issue Preserve C# constructor invocation arity after using-alias normalization #5189 / Make inspect selectors reusable and keep overload bundles identity-scoped #5159 / Resolve constructor navigation by symbol identity instead of partial-type name #4850 and reference-resolution query-plan tests — 46 passed on each of net8.0 and net9.0
• Full net8.0 suite — 12,005 passed, 9 skipped, 0 failed
• Full net9.0 suite — 11,521 passed, 430 skipped, 0 failed
• dotnet run --project tools/CodeIndex.Changelog -- check — 7 fragments validated
• Dogfood index refresh and checks — index matches HEAD, workspace healthy, graph ready
• Dogfood constructor evidence — a real two-argument Regex alias call resolves uniquely to BoundedRegex(string, RegexOptions)

Documentation and changelog

• Updated the English and Japanese constructor-resolution contracts in DEVELOPER_GUIDE.md and TESTING_GUIDE.md.
• Added bilingual fragment changelog.d/unreleased/5189.fixed.md.

Adversarial review

• Ran the required Codex adversarial review for two rounds, the workflow maximum.
• Addressed all six actionable findings: lexical token collisions, colon classification, escaped @params, primary/explicit family binding, ambiguous relational/interpolated expressions, and overflow-safe persisted-span validation.
• Rebuilt and reran focused and full cross-target validation after the final fixes.

Follow-up candidates

• None.

Fixes #5189