fix: enable compiled Source binding to resolve XamlC XC0025 in TodoApp.MAUI

[adrianhall]

Summary

Fixes #517.

MainPage.xaml's Entry.ReturnCommandParameter binds via an explicit Source={x:Reference addItemEntry} instead of the page's BindingContext. By default, XamlC skips compiling any binding with an explicit Source, which produced this build warning (performance-only, no functional impact):

MainPage.xaml(58,25): XamlC warning XC0025: Binding was not compiled because it has an explicitly set Source property and compilation of bindings with Source is not enabled. ...

Fix

Per current .NET MAUI docs on compiling Source bindings:

1. TodoApp.MAUI.csproj: opt in to <MauiEnableXamlCBindingWithSourceCompilation>true</MauiEnableXamlCBindingWithSourceCompilation> project-wide, with a comment explaining why and confirming this is the only Source-based binding in the project (so there's no risk of newly-surfaced x:DataType mismatches elsewhere, per the doc's own caution about this being an opt-in feature).
2. MainPage.xaml: annotate the binding itself with the documented inline x:DataType=Entry so XamlC has the type info it needs to compile it: {Binding Text, Source={x:Reference addItemEntry}, x:DataType=Entry}.

This avoids any XAML restructuring — no DataTemplate/binding-scope changes needed, since MAUI 9+ supports annotating the Binding markup extension directly.

Verification

Local verification wasn't possible (macOS host, no MAUI workloads installed, no Windows target available), so I triggered build-samples.yml manually via workflow_dispatch on the fork and inspected the raw job logs:

• todoapp-windows / build (the job that originally surfaced this warning): run — 0 occurrences of XC0025 in the build log; only the pre-existing, unrelated CS0618 ListView is obsolete warning remains (same warning present before this change).
• todoapp-maui / android and todoapp-maui / ios: also clean — no XC0025, no new XC00xx warnings.
• All 18 jobs in the build-samples.yml run passed.

Related

• Add CI workflow to build Windows-only /samples heads (Phase 2 of #509) #510 / ci: add build-samples workflow for Phase 2 Windows-only heads (#510) #514 — where this warning was first surfaced when Windows CI coverage was added for TodoApp.MAUI.