docs: add a screenshot to the Texture Mods (gMod) page

Show the gMod panel - active status/version, the pack list with
load-order and remove controls, and the Loaded DirectX9 Textures
capture gallery - placed after the intro. Stored as webp to match the
other docs-images screenshots.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: henderkes

site/public/docs-images/texmod_window.webp

@@ -9,6 +9,8 @@ Toolbox can load texture replacement packs at runtime using a built-in [gMod](ht
 
 gMod itself is downloaded and kept up to date automatically into your Toolbox folder — there's nothing to install. The status line shows whether gMod is active, and the version row offers a manual **Check for gMod updates** if you want to force a re-check.
 
+<img src="/docs-images/texmod_window.webp" alt="The gMod/uMod/Texmod settings panel: the gMod active status and version row, the texture pack list with load-order and remove controls, and the expanded Loaded DirectX9 Textures capture gallery" />
+
 ## Adding packs
 
 Click **Add texture pack** and pick a file. Supported formats: