PowerToys Explorer shell extensions do not support legacy context menu mode on Windows 11 (via registry tweak)

### Description of the new feature / enhancement

Please consider adding fallback compatibility for legacy context menu environments on Windows 11, including systems using the common legacy menu registry tweak.

Possible implementation directions:

1. Register legacy shell extension handlers in parallel with modern Win11 context menu handlers where feasible
2. Provide an optional compatibility mode / setting to force legacy shell extension registration
3. Document explicitly if legacy context menu support is intentionally unsupported

Even if full support is not planned, an official clarification would be appreciated, since this registry tweak remains widely used by power users due to performance/usability concerns with the Windows 11 context menu.

### Scenario when this would be used?

PowerToys Explorer shell extensions (PowerRename / Image Resizer / File Locksmith) do not appear when Windows 11 is forced into legacy context menu mode via the common {86ca1aa0-34aa-4e8b-a509-50c905bae2a2} registry hack, while they work correctly in the default Windows 11 context menu.

This appears to indicate that current PowerToys shell integration depends on the Windows 11 modern context menu pipeline and lacks compatibility/fallback support for the legacy context menu path.

Legacy context menu is enabled using the widely adopted registry tweak:

```
Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Classes\CLSID\{86ca1aa0-34aa-4e8b-a509-50c905bae2a2}]
[HKEY_CURRENT_USER\Software\Classes\CLSID\{86ca1aa0-34aa-4e8b-a509-50c905bae2a2}\InprocServer32]
@=""
```

### Supporting information

### Why this matters

Many advanced users intentionally enable legacy context menus because:

Windows 11 modern context menu is slower
Modern menu introduces extra clicks / UI friction
Legacy menu provides more predictable shell extension behavior

Currently this creates a usability conflict between PowerToys Explorer features and legacy context menu workflows.

Reproduce the issue with PowerRename, Image Resizer, or File Locksmith on Windows 11 after applying the documented registry tweak. Start by tracing how these Explorer shell extensions are registered and compare their behavior in modern and legacy context menus. Done means compatibility is implemented, or the supported and unsupported behavior is clearly documented.

Written by the indexing model from the issue text.