CmdPal: Reorder Pin to Dock dialog so controls precede the preview (#48250)

## Summary of the Pull Request

Reorder the Pin to Dock dialog content so the configuration controls
(monitor selector, dock section, label options) appear at the top and
the live preview is shown below them. The user now configures the pin
first and sees the resulting preview directly underneath, instead of
staring at the preview and having to scan past it to find the controls.

<img width="515" height="440" alt="image"
src="https://github.com/user-attachments/assets/0d1d0543-2b30-48f5-a1aa-676a165870f5"
/>

## PR Checklist

- [ ] Closes: #xxx
- [x] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [x] **Tests:** Added/updated and all pass
- [x] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places

## Detailed Description of the Pull Request / Additional comments

XAML-only change to
`src/modules/cmdpal/Microsoft.CmdPal.UI/Dock/PinToDockDialogContent.xaml`.
The new visual order inside the `ScrollViewer`/`StackPanel` is:

1. Monitor selector (still `Visibility=""Collapsed""` by default; shown
when more than one monitor is available)
2. Dock section `Segmented` (Start / Center / End)
3. Label options (`Show title` / `Show subtitle` checkboxes)
4. Divider `Rectangle`
5. Preview `Border`

No logic, bindings, `x:Name` identifiers, event handlers, or `x:Uid`
keys are changed.

## Validation Steps Performed

- Built `Microsoft.CmdPal.UI` (Debug arm64) — clean.
- Verified the Pin to Dock dialog renders with controls on top and the
preview underneath; segmented selection, label-option checkboxes, and
the multi-monitor combo still behave as before.

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>