[FEATURE]: More control over mouse capture in TUI

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

The current setting for mouse capture in TUI is to either have it enabled, or fully disable it.

I would like a more granular control over which features of the mouse capture I want to use.

For instance, instead of :

{
    ...
    "mouse": true, // or "mouse": false
}

I would like to be able to write :

{
    ...
    "mouse": {
        "scroll": true, // I want to use the mouse scrolling normally
        "select": false, // I DONT want opencode to override my terminal's select behavior, I have it customized how I like it (lots of users seem to complain of related selection issues)
        "click": true, // I want to use the click features to toggle subagents / thinking blocks / tool blocks
        "move_cursor_on_click": false // I DONT want opencode to move the cursor when I click around my text prompt
    }

Theses are the options I would personally need (and I'm sure a lot of people would like similar options) but I would not be opposed to have access to even more control if it makes sense.

Mouse capture is a pretty useful but invasive feature, which means that its difficult to live without it but it has a lot of drawbacks. In order to properly balance theses 2 aspects of it, users need as much control as possible over it.

For backward compatibility, "mouse": true or "mouse": false would just enable or disable every mouse feature as it currently does.