[P2][HR][Gaps][Navigation][Test] Add regression test for switching ViewMap to DataViewMap at runtime

[kazo0]

Source

Sub-issue of unoplatform/private#926. Tracked from the HR + Navigation test matrix.

Status from matrix

Works — verified during the manual HR pass against the Chefs sample.

Scenario

In App.xaml.host.cs, change new ViewMap<HomePage, HomeModel>() to new DataViewMap<HomePage, HomeModel, SearchFilter>() while the app is running. After HR, routes targeting HomeModel continue to work with SearchFilter being passed as data.

Goal

This scenario was reported as working under HR. To prevent future regressions, we need a Hot Reload regression test in the Uno.Extensions HR testharness that exercises this exact scenario by triggering the relevant edits at runtime and asserting expected post-HR behavior.

Acceptance

• Regression test added in the HR testharness covering: Switch ViewMap → DataViewMap (No-Data → Data) at runtime and assert routes targeting the page now pass data
• Test runs as part of CI on the relevant platforms