docs(config): document XDG_DATA_HOME support on Windows and macOS

- Update XDG_DATA_HOME section to show cross-platform support
- Add PowerShell example for Windows
- Update getting-started to mention all platforms support XDG

Closes #12

Author: CalvinAllen

website/src/content/docs/user-guide/configuration.md

@@ -28,15 +28,24 @@ $env:DTVEM_ROOT = "C:\custom\path\dtvem"
 - macOS: `~/.dtvem`
 - Windows: `%USERPROFILE%\.dtvem`
 
-### XDG_DATA_HOME (Linux only)
+### XDG_DATA_HOME
 
-On Linux, dtvem follows the [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html). If `XDG_DATA_HOME` is set, dtvem uses `$XDG_DATA_HOME/dtvem`.
+dtvem supports the [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html) on all platforms. When `XDG_DATA_HOME` is set, dtvem uses `$XDG_DATA_HOME/dtvem` as its root directory.
 
 ```bash
-export XDG_DATA_HOME=~/.local/share  # Default
+# Linux/macOS
+export XDG_DATA_HOME=~/.local/share
 # dtvem will use ~/.local/share/dtvem
 ```
 
+```powershell
+# Windows (PowerShell)
+$env:XDG_DATA_HOME = "$env:USERPROFILE\.local\share"
+# dtvem will use %USERPROFILE%\.local\share\dtvem
+```
+
+When `XDG_DATA_HOME` is not set, dtvem uses the default locations shown above.
+
 **Note:** `DTVEM_ROOT` takes priority over `XDG_DATA_HOME`.
 
 ### DTVEM_VERBOSE

website/src/content/docs/user-guide/getting-started.md

@@ -29,7 +29,7 @@ curl -fsSL dtvem.io/install.sh | bash
 | macOS | `~/.dtvem` | `~/.dtvem/shims` |
 | Linux | `~/.local/share/dtvem` | `~/.local/share/dtvem/shims` |
 
-On Linux, dtvem follows the [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/latest/). If `$XDG_DATA_HOME` is set, dtvem uses `$XDG_DATA_HOME/dtvem` instead.
+On all platforms, dtvem supports the [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/latest/). If `$XDG_DATA_HOME` is set, dtvem uses `$XDG_DATA_HOME/dtvem` instead.
 
 ## Custom Installation