Let me set a default main monitor

### Feature Description

Have a checkbox or the ability to move the monitors settings blocks to reflect the priority of them while assigning the initial workspaces in hypr

### Use Case

I really wish there was an option to set a main monitor. I have 2 screens and for some reason my 2nd monitor always turns on first, so the 1st workspace always its assigned there. I did change the hyprconfig but yeah I its replaced by the shell.

### Compositor(s)

All compositors

### If Other, please specify

_No response_

### Proposed Solution

add an option to choose a main monitor

### Alternatives/Existing Solutions

_No response_

Start by locating the monitor settings blocks and the logic that assigns initial workspaces in the shell. Compare how monitor ordering is handled for the supported compositors, then define the setting's expected behavior; done means users can choose a default main monitor instead of relying on compositor startup order.

Written by the indexing model from the issue text.