UserStory | More options for SideBar backgrounds in themes

### 🎭 The Who - What - Why

As a user I want to be able to set images and blur options as a custom theme css rules.

### 🧐 Additional Context

Idea by aarongamingdevtv

### 🎮 User-Side Criteria

_No response_

### 🔧 Dev-Side Criteria

_No response_

### 📐 Application Section

🔗 API