Volume bar not displayed when volume is at 100%

### Feature Description

## Description:
When I try to increase the volume while it is already at 100%, the on-screen volume indicator does not appear. This makes it difficult to know that the volume is already maxed out and prevents me from stopping attempts to increase it.

## Steps to Reproduce:

1. Set the system/app volume to 100%.
2. Attempt to increase the volume.
3. Observe that the volume bar/indicator does not appear on screen.

## Expected Behavior:
The volume bar should appear, even at maximum volume, to indicate that the volume is full.

## Actual Behavior:
The volume bar does not show at all when the volume is at 100%.

## Environment:
- OS: CachyOS
- Window Manager: Hyprland
- App Version: dms v1.4.3
- API Version: v24

### Use Case

_No response_

### Compositor(s)

All compositors

### If Other, please specify

_No response_

### Proposed Solution

_No response_

### Alternatives/Existing Solutions

_No response_

Start by tracing the volume-increase handling and the on-screen volume indicator's visibility logic in DankMaterialShell. Reproduce the issue at 100% volume, then verify that the indicator appears when another increase is attempted and remains correct at the maximum level.

Written by the indexing model from the issue text.