[UITests] New framework around WinApp CLI, no WinAppDriver or Selenium. (#48467)

# Add winappcli-based UI test harness (no WinAppDriver / Selenium)

## Summary

Introduces a new UI test harness — `Microsoft.PowerToys.UITest.Next` —
that drives PowerToys
modules through Microsoft's
[winappcli](https://github.com/microsoft/WinAppCli) (UI Automation
CLI) instead of WinAppDriver + Selenium. Engine is a single executable
shelled out from
C#; no third-party NuGet packages, no driver process, no Appium server.
Adds two real consumers:
a full ColorPicker end-to-end scenario and a Settings shell navigation
smoke test.

This is opt-in and additive — the existing `UITestAutomation` library
and the
WinAppDriver-based test projects are untouched. Both can coexist while
we evaluate the new
harness.

Inspired in part by
[#48414](https://github.com/microsoft/PowerToys/pull/48414), which lands
the same architectural bet (winappcli, AutomationId selectors, no
WinAppDriver) at a smaller
scope. This PR generalizes it into a reusable library.

## Why

WinAppDriver + Selenium is a legacy pre-agentic solution that is no
longer actively maintained. It's unreliable, heavyweight, and slow. To
achieve 100% UI test coverage, we should leverage modern, reliable
solutions, and WinApp CLI is a strong candidate.

## What's in this PR

### Harness library —
[`src/common/UITestAutomation.Next/`](src/common/UITestAutomation.Next/)

| File | Purpose |
|---|---|
| [`WinappCli.cs`](src/common/UITestAutomation.Next/WinappCli.cs) |
Process wrapper around `winapp.exe`. `Invoke` / `InvokeAssertSuccess` /
`InvokeJson` / `IsAvailable` / `TryResolveExecutable`. `Result` carries
the args and emits `DescribeFailure()` like `winapp ui invoke X -w 12345
-> exit 1; stderr: ...` |
| [`Session.cs`](src/common/UITestAutomation.Next/Session.cs) | Test
session, scoped by either HWND (`-w`) or process (`-a`) via
`TargetScope`. `Find<T>` / `FindAll<T>` / `Inspect` / `Screenshot` /
`SendKeys`. `Session.FromProcess(...)` factory for the
single-window-per-process case |
|
[`SessionHelper.cs`](src/common/UITestAutomation.Next/SessionHelper.cs)
| Owns the launch + window-readiness flow. Static `EnsureRunning(scope,
timeout)` returns whether the call had to launch (so cleanup only kills
what we started). Uses `UseShellExecute=true` so child handles don't
keep MSTest hanging |
| [`UITestBase.cs`](src/common/UITestAutomation.Next/UITestBase.cs) |
MSTest base class. Pre-flights `WinappCli.IsAvailable()` once per
process and fails fast with the install hint if `winapp.exe` isn't on
PATH |
| [`Element/*.cs`](src/common/UITestAutomation.Next/Element/) |
`Element`, `Button`, `ToggleSwitch`, `TextBox`, `NavigationViewItem`,
`Window`. `Click` / `MouseClick` / `Focus` / `GetProperty` / `GetValue`
/ `HelpText` / `WaitForProperty` / `WaitForGone` plus coords
(`X`/`Y`/`Width`/`Height`) |
| [`By.cs`](src/common/UITestAutomation.Next/By.cs) | `By.Name` /
`By.AccessibilityId` / `By.Id` / `By.Slug` |
| [`Windows.cs`](src/common/UITestAutomation.Next/Windows.cs) |
`WindowsFinder.ListAll` / `ListByApp` / `WaitForWindowByApp` /
`WaitForWindowByProcess`. Notes the winappcli bug where unfiltered
`list-windows` drops untitled windows |
|
[`WindowControl.cs`](src/common/UITestAutomation.Next/WindowControl.cs)
| Tolerant Win32 helpers — `TryCloseByApp` / `TryFocusByApp` /
`SafeCloseAndFocus` / `TryKillProcess` — for `finally` blocks |
|
[`KeyboardHelper.cs`](src/common/UITestAutomation.Next/KeyboardHelper.cs)
| Hybrid `keybd_event` + `SendKeys.SendWait` chord sender — required for
global PowerToys hotkeys |
| [`MouseHelper.cs`](src/common/UITestAutomation.Next/MouseHelper.cs) |
`MoveTo` / `LeftClick` / `RightClick` / `LeftClickAt` Win32 wrappers |
|
[`ClipboardHelper.cs`](src/common/UITestAutomation.Next/ClipboardHelper.cs)
| STA-thread `Clipboard` access with `WaitForText` |
|
[`ModuleConfigData.cs`](src/common/UITestAutomation.Next/ModuleConfigData.cs)
| `PowerToysModule` enum + path/process-name resolution |

### Tests


**[`src/modules/colorPicker/ColorPicker.UITests/`](src/modules/colorPicker/ColorPicker.UITests/)**
— replaces the previous empty `UITest-ColorPicker` stub. One test,
[`ColorPickerEndToEndTests.NavigateReadShortcutActivateAndCapture`](src/modules/colorPicker/ColorPicker.UITests/ColorPickerEndToEndTests.cs),
drives the full E2E:
1. Navigate to the Color Picker page via the dashboard utilities stack
2. Toggle the module OFF, verify `PowerToys.ColorPickerUI` exits; toggle
ON, verify it respawns
3. Read the activation shortcut from the page's `ShortcutControl`
(`EditButton.HelpText`)
4. Clear clipboard, park cursor, send the chord
5. Wait for the picker overlay window
6. Read the displayed HEX from a hidden XAML automation peer (see below)
7. Left-click to capture; assert the clipboard value matches the peer's
HEX
8. Wait for the editor window and assert the captured color appears in
its tree


**[`src/settings-ui/Settings.UITests/`](src/settings-ui/Settings.UITests/)**
— `SettingsNavigationSmokeTests.NavigationItem_NavigatesWithoutCrashing`
is one `[TestMethod]` parameterized with `[DynamicData]`, producing 31
discrete results — one per `NavigationViewItem` in
[`ShellPage.xaml`](src/settings-ui/Settings.UI/SettingsXAML/Views/ShellPage.xaml).
For each item: navigate, settle 250ms, assert `PowerToys.Settings` is
still alive. Catches FailFast regressions in
`ShellViewModel.Frame_NavigationFailed` that pure-logic unit tests can't
reach (the failure path needs a `NavigationFailedEventArgs` which is a
sealed WinRT projection).

### Product change


**[`src/modules/colorPicker/ColorPickerUI/Views/MainView.xaml`](src/modules/colorPicker/ColorPickerUI/Views/MainView.xaml)**
— adds a hidden `TextBlock` automation peer:

```xml
<TextBlock
    x:Name="ColorHexAutomationPeer"
    AutomationProperties.AutomationId="ColorHexAutomationPeer"
    IsHitTestVisible="False"
    Opacity="0"
    Text="{Binding ColorText}" />
```

The visible `ColorTextBlock` has `AutomationProperties.Name="{Binding
ColorName}"`, which masks the HEX value in the UIA tree (you see "White"
instead of `#FFFFFF`). This zero-impact peer mirrors `ColorText` so
tests can read the actually-displayed HEX. `Opacity=0` +
`IsHitTestVisible=False` keep it out of the visual layout and out of
accessibility focus.

### Project wiring

- [`PowerToys.slnx`](PowerToys.slnx) — registers `UITestAutomation.Next`
under `/common/`, `ColorPicker.UITests` under
`/modules/colorpicker/Tests/`, and `Settings.UITests` under
`/settings-ui/Tests/`. Original `UITest-ColorPicker` stub csproj
removed.
-
[`.github/actions/spell-check/expect.txt`](.github/actions/spell-check/expect.txt)
— adds `winapp` / `winappcli`.

### Not in this PR

- No pipeline changes. `winapp.exe` is expected to be pre-staged on the
test agent image. If it's missing, `UITestBase` fails the first test
with the install hint (`winget install Microsoft.winappcli`) rather than
producing 30 opaque per-test errors.
- No changes to the legacy `UITestAutomation` library or any of the
existing `*.UITests` projects.

## Validation

- All three projects build clean on `x64|Debug` (empty
`build.<config>.<plat>.errors.log`):
  - `src/common/UITestAutomation.Next/`
  - `src/modules/colorPicker/ColorPicker.UITests/`
  - `src/settings-ui/Settings.UITests/`
- Both tests run in Test Explorer / `dotnet test` via
Microsoft.Testing.Platform (already enabled repo-wide in
`Directory.Build.props`).
- Local runs: ColorPicker E2E green; Settings smoke green across all 31
nav items.
- `winapp 0.3.2` from `winget install Microsoft.winappcli`.

## Notes for reviewers

- **`UseShellExecute = true`** in `SessionHelper.EnsureRunning` is
intentional — `false` makes child processes inherit the test host's
stdin/stdout/stderr handles, which keeps MTP/Test Explorer marking the
run as "in progress" until the spawned PowerToys exits.
- **Process-scope (`-a`) targeting** in the Settings smoke test handles
single-instance handoff: the EXE you launch may exit with code 0
immediately after signalling an existing owner, so the alive check uses
`Process.GetProcessesByName` rather than the launcher PID.
- **AutomationId-only selectors** in the Settings smoke list keep the
test localization-independent. Parent groups have
`SelectsOnInvoked="False"` and only expand on click — `Element.Click`
tries `InvokePattern → TogglePattern → SelectionItemPattern →
ExpandCollapsePattern` so the same call works for both leaves and
groups.
- **Untitled-window discovery**: filtered `winapp ui list-windows -a
<name>` returns windows that the unfiltered call drops (e.g. ColorPicker
editor). `WindowsFinder.ListByApp` uses the filtered form. Reported
upstream.

## Before Merge

- Add the `winappcli` install step to the UI-test pipeline.

Cpp.Build.props

@@ -66,7 +66,10 @@
       <LanguageStandard>stdcpplatest</LanguageStandard>
       <BuildStlModules>false</BuildStlModules>
       <!-- TODO: _SILENCE_STDEXT_ARR_ITERS_DEPRECATION_WARNING for compatibility with VS 17.8. Check if we can remove. -->
-      <PreprocessorDefinitions>_SILENCE_STDEXT_ARR_ITERS_DEPRECATION_WARNING;_UNICODE;UNICODE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <!-- TODO: _SILENCE_EXPERIMENTAL_COROUTINE_DEPRECATION_WARNINGS for VS 2026 (MSVC 14.51+). The STL turned
+           <experimental/coroutine> into a hard error (STL1011), and C++/WinRT's base.h still falls back to it when
+           __cpp_lib_coroutine isn't defined at include time. Remove once C++/WinRT no longer references the experimental header. -->
+      <PreprocessorDefinitions>_SILENCE_STDEXT_ARR_ITERS_DEPRECATION_WARNING;_SILENCE_EXPERIMENTAL_COROUTINE_DEPRECATION_WARNINGS;_UNICODE;UNICODE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <!-- CLR + CFG are not compatible >:{ -->
       <ControlFlowGuard Condition="'$(CLRSupport)' == ''">Guard</ControlFlowGuard>
       <DebugInformationFormat Condition="'%(ControlFlowGuard)' == 'Guard'">ProgramDatabase</DebugInformationFormat>