Support more file extensions for syntax highlighting

[markusfurtlehner]

Problem

The Monaco editor does not support syntax highlighting for all file types. This was originally reported for PS1 (PowerShell) files which had no highlighting.

The root cause was that getMonacoLang() in frontend/src/utils.ts only mapped ~10 file extensions, despite Monaco shipping with ~75 built-in languages.

Affected file types (reported)

• .ps1, .psm1, .psd1 (PowerShell)
• .cshtml, .razor (Razor)

Additional gaps

• File types not natively supported by Monaco (e.g., Nix, TOML) have no highlighting at all
• Extensionless files (e.g., Makefile, Dockerfile, .gitignore) may not be detected correctly