[Composition] Keyboard focus visual not shown when focus is set programmatically or via NavigateFocus into a newly-shown content island

Problem Description

In react-native-windows (Composition / Fabric), the keyboard focus ring
(focus visual) is drawn only after a real keyboard event has occurred
within a given ReactNativeIsland. When focus is placed programmatically
— either JS component.focus() or native
InputFocusNavigationHost.GetForSiteBridge(bridge).NavigateFocus(FocusNavigationRequest.Create(FocusNavigationReason.First))
— focus moves correctly (UIA/Narrator announces the element) but the island is
not put into the "show focus visuals" state, so no ring is rendered
until the user presses Tab/arrow inside that island.

The "keyboard mode" that enables the ring appears to be tracked per island:
a keypress that happened in island A does not enable focus visuals for a
programmatic focus placed into a freshly-shown island B.

Steps To Reproduce

1. Build an app with two Composition content islands (each its own
   ReactNativeIsland) — e.g. a main view and a popup/menu shown in a separate
   island.
2. Show the popup island and set focus on its first item, using either:
   • JS: firstItemRef.current.focus(), or
   • native: InputFocusNavigationHost.GetForSiteBridge(bridge).NavigateFocus(FocusNavigationRequest.Create(FocusNavigationReason.First))
3. Observe the item is focused (Narrator announces it) but no focus ring is drawn.
4. Press Tab or an arrow key → the focus ring now appears and behaves correctly.

Expected Results

When focus is moved with a keyboard navigation reason
(First / Last / directional), RNW should render the focus visual — matching
XAML/WinUI FocusState.Keyboard semantics. At minimum, there should be a way to
request keyboard focus visuals when setting focus programmatically (so a menu/
popup that opens via keyboard shows a ring on its initial item, and focus
restored to a caller after dismissing a popup shows a ring).

Actual results:
No focus ring is drawn on the initially focused element until the user presses
a key in that island. enableFocusRing is true on the components (the ring
renders correctly once keyboard navigation occurs).

Investigation suggests the NavigateFocusRequested handling moves focus but
ignores the FocusNavigationReason for focus-visual purposes, so even the
native NavigateFocus(...First) path does not enable the ring.

CLI version

CLI 0.81.3

Environment

- react-native-windows: 0.81.5
- @react-native-windows/cli: 0.81.3
- react-native: 0.81.5
- UI library: @fluentui/react-native 0.42.24 (ButtonV1, enableFocusRing)
- Architecture: Composition / Fabric, DesktopChildSiteBridge content islands
- Windows App SDK: bundled via host app (1.x)
- OS: Windows 11 (x64)

Community Modules

No response

Target React Native Architecture

None

Target Platform Version

None

Visual Studio Version

None

Build Configuration

None

Snack, code example, screenshot, or link to a repository

No response

Start at the NavigateFocusRequested handling and trace how FocusNavigationReason is used when focus moves into a newly-shown ReactNativeIsland. Reproduce both the JS component.focus() and native NavigateFocus(...First) paths with Composition/Fabric islands. Done means keyboard-reason focus shows the ring immediately, including focus restored after a popup closes, without regressing existing keyboard navigation.