Unsupported Distribution 'gentoo' when running install script

### Compositor

Niri

### Distribution

Gentoo

### If Other, please specify

_No response_

### Select your Installation Method

DankInstaller

### Was this your original Installation method?

No (specify below)

### If no, specify

DankInstall didn't work so I used an overlay (https://danklinux.com/docs/dankmaterialshell/installation#tdgentoo) to install DMS. But Gentoo is listed as a supported distribution for DankInstall so it should also work.

### dms doctor -vC

Click to expand
## DMS Doctor Report

**System**
- [warn] Operating System: 'Gentoo Linux' (not supported by dms setup)
- DMS may work but automatic installation is not available
- [ok] Architecture: amd64
- [ok] Display Server: Wayland
- WAYLAND_DISPLAY=wayland-1

**Versions**
- [ok] DMS CLI: dms dev
- /usr/bin/dms
- [ok] Quickshell: Quickshell 0.2.1 (revision , distributed by Gentoo GURU)
- /usr/bin/qs
- [ok] DMS Shell: v1.4.4
- /usr/share/quickshell/dms

**Installation**
- [ok] DMS Configuration: Found
- /usr/share/quickshell/dms
- [ok] shell.qml: Present
- /usr/share/quickshell/dms/shell.qml
- [info] Install Type: System package
- /usr/share/quickshell/dms

**Compositor**
- [ok] niri: 25.11
- /usr/bin/niri
- [info] Active: niri
- [warn] Background Blur: Unsupported
- Compositor does not support ext-background-effect-v1

**Quickshell Features**
- [ok] Polkit: Available
- Authentication prompts
- [ok] IdleMonitor: Available
- Idle detection
- [ok] IdleInhibitor: Available
- Prevent idle/sleep
- [ok] ShortcutInhibitor: Available
- Allow shortcut management (niri)
- [ok] BackgroundBlur: Available
- Background blur API support in Quickshell

**Optional Features**
- [warn] accountsservice: Not available
- User accounts
- [warn] power-profiles-daemon: Not available
- Power profile management
- [ok] logind: Available
- Session management
- [warn] cups-pk-helper: Not available (install cups-pk-helper)
- Printer management
- [info] I2C/DDC: No monitors detected
- External monitor brightness control
- [ok] qt6-imageformats: Installed (1 formats)
- Formats: GIF (/usr/lib64/qt6/plugins/imageformats)
- [warn] kimageformats: Not installed
- AVIF, HEIF, JXL support
- [ok] Terminal: alacritty, foot
- [ok] Network: NetworkManager
- NetworkManager present. Using NM API.
- [ok] matugen: Installed
- Dynamic theming
- [ok] dgop: Installed
- System monitoring
- [ok] cava: Installed
- Audio visualizer
- [info] khal: Not installed
- Calendar events
- [ok] danksearch: Installed
- File search
- [info] fprintd: Not installed
- Fingerprint auth

**Config Files**
- [ok] settings.json: Present
- /home/yaslam/.config/DankMaterialShell/settings.json
- [info] clsettings.json: Not yet created
- /home/yaslam/.config/DankMaterialShell/clsettings.json
- [info] plugin_settings.json: Not yet created
- /home/yaslam/.config/DankMaterialShell/plugin_settings.json
- [ok] session.json: Present
- /home/yaslam/.local/state/DankMaterialShell/session.json
- [ok] dms-colors.json: Present
- /home/yaslam/.cache/DankMaterialShell/dms-colors.json

**Services**
- [ok] dms.service: enabled, active
- [info] greetd: Not installed
- Optional greeter service

**Environment**
- [info] QT_QPA_PLATFORMTHEME: qt5ct
- [info] QS_ICON_THEME: Not set

---
**Summary:** 0 error(s), 6 warning(s), 25 ok

### Description

When running DankInstall, it shows me this output on Gentoo:
```

██████╗ █████╗ ███╗ ██╗██╗ ██╗
██╔══██╗██╔══██╗████╗ ██║██║ ██╔╝
██║ ██║███████║██╔██╗ ██║█████╔╝
██║ ██║██╔══██║██║╚██╗██║██╔═██╗
██████╔╝██║ ██║██║ ╚████║██║ ██╗
╚═════╝ ╚═╝ ╚═╝╚═╝ ╚═══╝╚═╝ ╚═╝

Installation Failed

✗ Unsupported distribution: 'gentoo'

Press Ctrl+D for full debug logs

Full logs: /tmp/dankinstall-1777877689.log
Press Enter to exit
```

This is strange, as Gentoo is listed as a supported distribution for DankInstall here: https://danklinux.com/docs/dankinstall#gentoo

This was also a fresh Stage 3 SystemD system, not a container or anything.

This is my `/etc/os-release`:
```
NAME='Gentoo'
ID='gentoo'
PRETTY_NAME='Gentoo Linux'
VERSION='2.18'
VERSION_ID='2.18'
HOME_URL='https://www.gentoo.org/'
SUPPORT_URL='https://www.gentoo.org/support/'
BUG_REPORT_URL='https://bugs.gentoo.org/'
ANSI_COLOR='1;32'
```

This error is not a big deal as DMS is packaged in the overlays (which is how I installed DMS), but DankInstall shouldn't say it supports Gentoo if it doesn't.

### Expected Behavior

DankInstall working on Gentoo Linux.

### Steps to Reproduce

1. Run DankInstall on Gentoo Linux

### Error Messages/Logs

_No response_

### Screenshots/Recordings

_No response_

Start with DankInstall's distribution detection and compare it with the reported /etc/os-release values for Gentoo. Check the DankInstall documentation entry for Gentoo as well. Done means DankInstall handles a supported Gentoo system, or the support claim and installation guidance are corrected to match its actual behavior.

Written by the indexing model from the issue text.