Unable to change aspect ratio on widescreen

# Unable to change aspect ratio on widescreen – forced black bars

## Category
Graphics / Display

## Description
It’s impossible to change or customize the game’s aspect ratio on ultrawide or super-ultrawide displays.  
I want to play full screen at **7680×2160** but limit the in-game rendering width to **5120** (with black bars on the sides) to improve multiplayer performance.

## Current behavior
- Game forces full native width in full-screen mode.  
- No way to set a smaller horizontal render width while staying full screen.  
- No option to keep correct proportions with side black bars.  
- No custom aspect ratio or horizontal resolution scaling control.

## Expected behavior
Allow full-screen at a custom render width (for example, **5120×2160**) on ultrawide displays, centered with black bars on the sides.

## Steps to reproduce
1. Use a 32:9 display or any monitor wider than 21:9.  
2. Set resolution to native (e.g., **7680×2160**).  
3. Reduce in-game rendering width to **5120**.  
4. Observe stretch or windowed output instead of a centered image with side black bars.

## Impact
Players on ultrawide setups can’t lower rendering load efficiently while keeping full-screen immersion, which affects multiplayer performance.

## System details
- Display: **7680×2160 (dual-UHD)**  
- Desired render area: **5120×2160**  
- Mode: **Full screen**

## Suggested solution
Add an **aspect ratio override** or **horizontal resolution scaling** option that keeps full screen with side black bars when rendering at a lower width.