Italic Cyrillic is broken in Nerd fonts

[Oreolek]

Issue Description

font issues: т and п

Expected Behavior

Compare the "т" and "п" in Ghosttty with other emulators. It should look like Italic "т" and "п". No ligatures, no accents or diacritic marks.

Actual Behavior

These do not look like Cyrillic or any real characters.

Reproduction Steps

echo -e '\033[3mтпоср\033[0m'

Ghostty Logs

No response

Ghostty Version

Ghostty 1.3.1-r582.g2897245-1-arch

Version
  - version: 1.3.1-r582.g2897245-1-arch
  - channel: tip
Build Config
  - Zig version   : 0.15.2
  - build mode    : .ReleaseFast
  - app runtime   : .gtk
  - font engine   : .fontconfig_freetype
  - renderer      : renderer.generic.Renderer(renderer.OpenGL)
  - libxev        : io_uring
  - kernel version: 7.0.0-rc7-273-tkg-bore
  - desktop env   : other
  - GTK version   :
    build         : 4.22.2
    runtime       : 4.22.2
  - libadwaita    : enabled
    build         : 1.9.0
    runtime       : 1.9.0
  - libX11        : enabled
  - libwayland    : enabled

OS Version Information

Arch Linux

(Linux only) Display Server

Wayland

(Linux only) Desktop Environment/Window Manager

sway

Minimal Ghostty Configuration

font-family = "Inconsolata LGC Nerd Font Mono"
font-family-bold = "Inconsolata LGC Nerd Font Mono Bold"
font-family-italic = "Inconsolata LGC Nerd Font Mono Italic"
font-family-bold-italic = "Inconsolata LGC Nerd Font Mono Bold Italic"

this is also observed on other Nerd-patched fonts. Chose Inconsolata to show the problem is still present with explicitly configured italic and bold italic fonts.

### Additional Relevant Configuration

_No response_

### I acknowledge that:

- [X] I have reviewed the FAQ and confirm that my issue is NOT among them.
- [X] I have searched the Ghostty repository (both open and closed Discussions and Issues) and confirm this is not a duplicate of an existing issue or discussion.
- [X] I have checked the "Preview" tab on all text fields to ensure that everything looks right, and have wrapped all configuration and code in code blocks with a group of three backticks (` ``` `) on separate lines.