[PowerDisplay] Add profile reordering

[Yu Leng (moooyo)]

Summary of the Pull Request

Allow users to reorder saved Power Display profiles without deleting and recreating them. Add drag-and-drop sorting and Move up/Move down menu actions, and persist the display position in a separate order field while retaining stable integer profile IDs.

PR Checklist

• Closes: Rearrangeable "Power Display" profiles #50425
• Communication: Maintainer review is pending.
• Tests: Added/updated; 629 relevant tests pass locally.
• Localization: Added Settings UI strings use resource entries.
• Dev docs: Updated doc/devdocs/modules/powerdisplay/design.md.
• New binaries: Not applicable; no new projects, binaries, or dependencies.
• Documentation updated: Public documentation follow-up is not included.

Detailed Description of the Pull Request / Additional comments

• In src/settings-ui/Settings.UI/SettingsXAML/Views/PowerDisplayPage.xaml and src/settings-ui/Settings.UI/ViewModels/PowerDisplayViewModel.cs, add a reorderable profile list with drag handles, bounded scrolling, and keyboard-accessible Move up/Move down actions. Elevated Settings retains menu-based sorting with native drag/drop disabled, following Mouse Without Borders.
• In src/modules/powerdisplay/PowerDisplay.Models/, use a contiguous zero-based order field independently of integer id and the physical JSON array. Editing preserves the saved position; new profiles use the existing nextId counter and append to the display order.
• Normalize missing or invalid order values under the existing profile-store mutex. Reordering changes only order values in the latest stored collection, preserves concurrent additions and edits, and refreshes the flyout through the existing settings notification. Failed saves/reloads retain the last known saved order in Settings.
• Preserve integer profile IDs, Light Switch references, and CLI/IPC schema version 1.0.

Validation Steps Performed

• Final Debug x64 builds succeeded for Settings UI and its test project, the Power Display app, and the Power Display Lib, Contracts, IPC, and CLI test projects.
• Ran the newly built assemblies through vstest.console.exe: Lib 341, Contracts 15, IPC 139, CLI 118, and relevant Settings ViewModel tests 16; 629 passed, 0 failed, 0 skipped.
• Coverage includes explicit order independent of array position and integer ID, stable IDs and nextId, order initialization, edit/append behavior, failed and concurrent writes, Light Switch references, elevated drag gating, CLI numeric-ID validation, and JSON/IPC round trips.
• git diff --check and XAML/XML parsing passed.
• Interactive UI validation remains pending: normal/elevated drag behavior, long-list scrolling, keyboard focus, and screen-reader behavior. This PR remains a draft.