[Bug]: Proton runner updates skip Proton font symlink maintenance and can leave broken font registry entries

[w568w]

Describe the bug

When Bottles uses a Proton build as a runner, it leaves relative Windows font registry values unresolved:

HKLM\Software\Microsoft\Windows NT\CurrentVersion\Fonts
  Tahoma (TrueType)      = tahoma.ttf
  Tahoma Bold (TrueType) = tahomabd.ttf

In my case, this caused a reproducible QtWebEngine crash in an existing bottle after every Proton update:

[ERROR:platform_font_skia.cc(343)] Could not find any font: Tahoma, sans. Falling back to the default
(Crashed at Qt5WebEngineCore.dll+0x28684ef)

which is a null pointer dereference from here, since even the default fonts resolve to non-existent paths.

To Reproduce

1. Create a 64-bit Gaming bottle using a Proton runner that ships files/share/wine/fonts/tahoma.ttf. For example, DWProton;
2. Update the proton version, let Bottles perform its normal runner/prefix update;
3. Query HKLM\Software\Microsoft\Windows NT\CurrentVersion\Fonts for Tahoma (TrueType), which should point to a non-existent relative path tahoma.ttf (i.e., drive_c/windows/Fonts/tahoma.ttf).

Package

Flatpak from Flathub

Distribution

Arch Linux

Debugging Information

Version: '66.9'
DE/WM: /usr/share/wayland-sessions/plasma.desktop
Display:
    X.org: true
    X.org (port): :0
    Wayland: true
Graphics:
    vendors:
        amd:
            vendor: amd
            envs:
                DRI_PRIME: '1'
            icd: /usr/share/vulkan/icd.d/radeon_icd.json
    prime:
        integrated: null
        discrete: null
    Vulkan: true
Kernel:
    Type: Linux
    Version: 7.2.2-1-cachyos
Disk:
    Total: 273670471680
    Free: 1091518464
RAM:
    MemTotal: 30.6GiB
    MemAvailable: 11.2GiB
Bottles_envs: null

Troubleshooting Logs

No obvious log.

Additional context

A quick workaround is manually replacing the font path values to absolute path (e.g., Z:\home\user\path\to\proton\files\share\wine\fonts\tahoma.ttf) in the registry (or just copy them to windows/Fonts/) after each update.

Wine refused to support an alternative font prefix, like /run/host/fonts.

So Proton has a create_fonts_symlinks() method to symlink them to windows/Fonts/, which is skipped by Bottles, causing this issue.