Host the manual's images in the repo under manual/images (#6861)

* Host the manual's images in the repo under manual/images

Replaces all learn.omacom.io/manual.omakub.org hotlinks with local webp
files capped at 1600px wide (~20MB total), so the manual is fully
self-contained. Theme and unlock previews are converted from the
canonical themes/*/preview.png files. A handful of illustration shots
are interim conversions of the current images, pending retakes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Retake the illustration screenshots fresh at 3x scaling

Navigation, clipboard history, notices, tmux layouts, prompt, and About
reshot on a clean workspace at 3.13x (1920x1080 logical on 6K) across
ten themes: Tokyo Night, Catppuccin, Gruvbox, Kanagawa, Everforest,
Nord, Osaka Jade, Rose Pine, Matte Black, and Ristretto.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Drop the extra themes chapter from the manual

The community theme gallery will live elsewhere. Removes the chapter
and its 114 gallery images, renumbers the following chapters, and
repoints the two references (theme installs still work via
Install > Style > Theme in the menu).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Reference the shipped theme previews instead of copying them

The themes chapter now points straight at themes/*/preview.png and
preview-unlock.png, so previews can never drift from the source and
manual/images drops from 6.3MB to 3.5MB.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

manual/26-gaming.md

@@ -14,7 +14,7 @@ After you've installed it, you'll be able to launch Steam with `Super + Space`.
 
 Note that Steam can take 10-20 seconds to start up, and it's not going to provide any visual feedback that it's loading.
 
- ![steam.png](https://learn.omacom.io/u/steam-tC5srj.png)
+ ![gaming-steam](images/gaming-steam.webp)
 
 ## RetroArch
 
@@ -30,7 +30,7 @@ To get going:
 
 You can also give a favorite game its own entry in the app launcher with _Install > Gaming > RetroArch Game Launcher_, which lets you pick a core and a ROM, and jump straight into the game from `Super + Space`.
 
- ![retroarch.jpg](https://learn.omacom.io/u/retroarch-wd6cuZ.jpg)
+ ![gaming-retroarch](images/gaming-retroarch.webp)
 
 ## Xbox Cloud Gaming
 
@@ -38,13 +38,13 @@ Install the Xbox Cloud Gaming web app by selecting _Install > Gaming > Xbox Clou
 
 If you already have Xbox Game Pass, this is a solid way to play Fortnite and other titles you can't run natively on Linux.
 
- ![xbox-cloud.jpg](https://learn.omacom.io/u/xbox-cloud-vEuyin.jpg)
+ ![gaming-xbox-cloud](images/gaming-xbox-cloud.webp)
 
 ## NVIDIA GeForce Now
 
 Install the cloud-gaming service [NVIDIA GeForce NOW](https://www.nvidia.com/en-us/geforce-now/) by selecting _Install > Gaming > NVIDIA GeForce NOW_ from the Omarchy menu (`Super + Space`). Another great way to play titles that aren't available natively on Linux.
 
- ![screenshot-2026-05-05_09-00-11-medium.jpg](https://learn.omacom.io/u/screenshot-2026-05-05_09-00-11-medium-tSjM9x.jpg)
+ ![gaming-geforce-now](images/gaming-geforce-now.webp)
 
 ## Minecraft
 
@@ -52,7 +52,7 @@ Install Minecraft by selecting _Install > Gaming > Minecraft_ from the Omarchy m
 
 Like Steam, note that it can take a while after logging in or starting up for the next screen to appear, and you're not going to get any feedback while you're waiting.
 
- ![screenshot-2026-05-05_09-02-39-medium.jpg](https://learn.omacom.io/u/screenshot-2026-05-05_09-02-39-medium-Vapoct.jpg)
+ ![gaming-minecraft](images/gaming-minecraft.webp)
 
 ## Xbox Controllers
 
@@ -70,7 +70,7 @@ You can also turn an Omarchy machine into the host by running `omarchy install s
 
 Install [Battle.net](https://eu.shop.battle.net/en-us) by selecting _Install > Gaming > Battle.net_ from the Omarchy menu (`Super + Space`). This gives you titles like Diablo, Starcraft, and World of Warcraft as a standalone install running under GE-Proton — no Steam, Lutris, or Heroic needed.
 
- ![starcraft.png](https://learn.omacom.io/u/starcraft-WU9zw7.png)
+ ![gaming-starcraft](images/gaming-starcraft.webp)
 
 ## Lutris (Windows games)