CmdPal: improve full-screen detection (#45891)

## Summary of the Pull Request

This PR improves fullscreen detection for the Command Palette activation
shortcut, adds a separate "busy state" guard, surfaces live notification
state diagnostics in Settings, and provides an opt-in rapid-press
breakthrough to bypass suppression.

The existing fullscreen guard lumped D3D fullscreen, presentation mode,
and the heuristic QUNS_BUSY state into a single check. This made it
impossible to opt into guarding against only true fullscreen while
ignoring false positives from apps like NVIDIA overlay. This PR splits
those concerns, adds diagnostic visibility, and gives users an escape
hatch.

The problem with the detection is that QUNS_RUNNING_D3D_FULL_SCREEN is
intended for exclusive D3D full-screen apps (some games), but it
overlaps with QUNS_BUSY for other games and apps.

  - Splits the fullscreen guard into two separate settings
- IsWindowFullscreen() now only checks QUNS_RUNNING_D3D_FULL_SCREEN and
QUNS_PRESENTATION_MODE
    - New IsAppBusy() handles the heuristic QUNS_BUSY state separately
- New IgnoreShortcutWhenBusy setting (off by default) so users aren't
silently blocked by false positives
- Migrates from hand-written P/Invoke (NativeMethods.cs, deleted) to
CsWin32-generated bindings
- Adds a live InfoBar in Activation settings when the shortcut is
limited
- Polls SHQueryUserNotificationState every 2 seconds via DispatcherTimer
- Displays a warning describing which state is active (D3D fullscreen,
presentation mode, or busy)
- New GetUserNotificationState() in WindowHelper exposes the raw state
for the UI
  - Attributes QUNS_BUSY to known trigger apps
- New FindVisibleTriggerApps() enumerates windows by class name and
process name against a known-app list
- When NVIDIA Overlay (or other known apps) are detected, the InfoBar
message names the likely culprit
  - Adds an opt-in rapid-press breakthrough to bypass suppression
    - New AllowBreakthroughShortcut setting (off by default)
- Pressing the activation shortcut 3 times within 2 seconds overrides
the guard
- The suppression is automatically bypassed when the Command Palette is
visible - to allow dismissal

## Pictures? Pictures!

<img width="1112" height="769" alt="image"
src="https://github.com/user-attachments/assets/e1d64ace-cfb2-4ba1-a436-3d2d77c18c76"
/>

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## PR Checklist

- [x] Closes: #45548
- [x] Closes: #41225
- [x] Closes: #42716
- [x] Closes: #45875
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- [ ] **Communication:** I've discussed this with core contributors
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- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
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for new binaries
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installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
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pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
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- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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## Detailed Description of the Pull Request / Additional comments

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