Mouse Utility: Add modifier key + scroll wheel window transparency control

### Description of the new feature / enhancement

AltSnap supports adjusting window transparency by holding a modifier key (e.g., Alt)
and scrolling the mouse wheel over any window. PowerToys already implements AltSnap's
window dragging and resizing via modifier key, but the transparency control feature
is missing.

Expected behavior:
- User holds a configurable modifier key (e.g., Alt or a custom key combo) and
scrolls the mouse wheel over any window.
- The target window's opacity/transparency is adjusted in real time based on
scroll direction (scroll up = more opaque, scroll down = more transparent).
- Minimum and maximum transparency thresholds should be configurable to prevent
windows from becoming fully invisible.
- The feature should be toggleable and integrated into the existing
Mouse Without Borders / FancyZones / Mouse Utilities section, or as an extension
to the current AltSnap-inspired "Mouse Jump" / drag utility.

### Scenario when this would be used?

Power users who work with multiple overlapping windows benefit greatly from being
able to quickly adjust window transparency without right-clicking or navigating
through app-specific settings. For example:

- A developer keeping API documentation visible behind their IDE.
- A writer referencing a source document behind their text editor.
- A trader monitoring a chart while typing in another window.

AltSnap users who migrate to PowerToys currently lose this workflow. Since
PowerToys has already adopted AltSnap's modifier-key window management paradigm,
adding transparency control would complete the feature parity and provide a
seamless transition for existing AltSnap users.

### Supporting information

_No response_

Start by reviewing PowerToys' existing Mouse Utilities, Mouse Without Borders, FancyZones, and AltSnap-inspired mouse features to determine where modifier-key handling and window interaction currently live. Define how configurable modifiers, opacity limits, toggling, and real-time scroll behavior should fit together, then verify the result against the expected scenarios in this issue.

Written by the indexing model from the issue text.