feat(render): add C# rendering prototype benchmarks

[2chevskii]

Summary

• Add an isolated C# display-name prototype and repeatable benchmark views under benchmarks/prototypes/ to measure the cost of the current PowerShell formatting path.
• Compare each display name and the complete table output before timing. The prototype currently covers the built-in NerdFonts glyph set, DefaultDark theme, ANSI output, and ordinary files and directories; it does not change the production module.
• On 3002 generated entries from master, median table times were 1043 ms for the current view, 388 ms with C# name rendering, and 240 ms with C# name rendering plus native Length (five measured iterations on Windows). Runtime prototype setup took 432 ms, including 411 ms of C# compilation.

Validation

• Pester tests — npm test: 62 passed.
• Documentation build, when documentation changed — npm run docs:build passed.
• Manual verification, when applicable — Measure-GlyPrototype.ps1 -ItemCount 3000 -Iterations 5: zero display-name and table-output mismatches.

Checklist

• The change is focused and does not include unrelated modifications.
• Tests and documentation have been updated where needed.
• I have read and agree to follow the Code of Conduct.