Feature request: option to display all workspaces independent of focused output in niri module

### Feature Description

I am using the workspaces widget with Niri and find the `Show workspace apps` feature effective for visualizing running applications. However, I have encountered a usability conflict in a specific multi-monitor configuration.

**Current setup:**

* **Environment:** Niri window manager with a dual-monitor setup.
* **Configuration:** Dank shell is configured as a vertical bar displayed on only *one* of the monitors.

**The issue:**
The workspace widget appears to be coupled to the currently focused output. This creates an interaction loop when the bar is not present on all screens:

1. When I focus on the second monitor (where the bar is not displayed), the bar on the first monitor updates to show the workspaces and apps of that second monitor.
2. To interact with those workspaces (e.g., to switch focus), I must move the cursor back to the first monitor where the bar is located.
3. Upon moving the cursor to the first monitor, the output focus shifts, causing the widget to immediately revert to showing the workspaces of the first monitor.
4. Consequently, the workspaces of the second monitor become unselectable via the mouse, as the widget state is transient and dependent on the cursor's location.

### Use Case

This feature is particularly relevant for vertical bar layouts where screen real estate is preserved by having a single dock for managing the entire session across multiple displays.

### Compositor(s)

- [ ] All compositors
- [x] Niri
- [ ] Hyprland
- [ ] MangoWC (dwl)
- [ ] Sway
- [ ] Other (specify below)

### Proposed Solution

I request an option to decouple the widget's view from the active output focus. Specifically, it would be useful to have a mode that displays **all workspaces from all monitors simultaneously** in the widget, or a "global" view that remains static regardless of which monitor is currently focused.

This would allow users to manage workspaces on secondary monitors without the widget state resetting during the mouse movement required to interact with the bar.

### Alternatives/Existing Solutions

_No response_

Begin by locating the Niri workspace widget/module and tracing how its focused output determines the displayed workspaces. Define the requested all-workspaces or global view and verify that it remains stable while focus moves between monitors. The issue names no files or tests, so repository exploration and design decisions are required.

Written by the indexing model from the issue text.