fix: suppress MT7156 duplicate BundleResource warnings on TodoApp.Uno ios/maccatalyst

[adrianhall]

Summary

The ios-maccatalyst head of TodoApp.Uno emits MT7156 warnings about duplicate BundleResource items during build:

warning MT7156: The BundleResource item '.../unoresizetizer/r/Assets/Icons/icon_foreground.png' was ignored, because there's another item with the same LogicalName ('Assets/Icons/icon_foreground.png')
warning MT7156: The BundleResource item '.../unoresizetizer/r/Assets/Images/back.png' was ignored, because there's another item with the same LogicalName ('Assets/Images/back.png')
warning MT7156: The BundleResource item '.../unoresizetizer/r/splash_screen.png' was ignored, because there's another item with the same LogicalName ('splash_screen.png')

Fixes #541

Root cause

Uno.Resizetizer (unoresizetizer) rasterizes each SVG-sourced asset (Assets/Icons/icon_foreground.svg, Assets/Images/back.svg, Assets/Splash/splash_screen.svg) into both an unscaled base PNG and an explicit scale-100 variant. On ios/maccatalyst, both collapse to the same BundleResource LogicalName, because Apple's bundling convention treats an unscaled asset and its 1x/scale-100 counterpart as identical — so one copy is silently dropped. The build still succeeds and the icon/splash render correctly; this is a warning about redundant bundling, not a missing or broken asset.

This is not a duplicate-inclusion bug in this project's Assets wiring: TodoApp.Uno.csproj has no explicit UnoIcon/UnoSplashScreen/UnoImage items — Uno.Sdk's Single Project convention auto-wires Assets/Icons/*.svg, Assets/Splash/*.svg, and Assets/Images/*.svg into the resizetizer pipeline implicitly, and this dual base+scale-100 emission on Apple TFMs is inherent Uno.Resizetizer output, confirmed by inspecting the CI job log directly (both net10.0-ios and net10.0-maccatalyst TargetFrameworks affected, for exactly the same three assets).

Why suppress rather than change the resource pipeline

This repo's CI only ever runs dotnet build for TodoApp.Uno (never publishes/packages the app), so the redundant bundling has no functional consequence in this pipeline. Attempting to reconfigure the UnoImage/UnoIcon/UnoSplashScreen pipeline to avoid the redundant scale-100 copy would require visual verification on an iOS/macCatalyst simulator (no Xcode available in this sandbox) and risks inadvertently affecting the Android/Windows heads, which legitimately need multiple scale variants from the same SVG sources.

Same fix pattern as #531/#548 (SuppressTrimAnalysisWarnings for the equivalent IL2026/IL2104 trim-analyzer noise): suppress the specific, confirmed-benign warning code via a precisely scoped MSBuild property, with a comment documenting the root cause.

Changes

samples/todoapp/TodoApp.Uno/TodoApp.Uno/TodoApp.Uno.csproj:

• Added MSBuildWarningsAsMessages for warning code MT7156, scoped to ios/maccatalyst only via the same $([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) conditional pattern already used for SuppressTrimAnalysisWarnings in this file.
• android/desktop/browserwasm/windows are intentionally left untouched — the CI job log confirms MT7156 (an Apple-toolchain-specific code) only ever appears on ios/maccatalyst.

Verification

• Negative control via CI: compared the ios-maccatalyst job log from the current main HEAD (ddd8c04, before this fix) against this branch's CI run.
  • Before: main's ios-maccatalyst job log shows 20 MT7156 occurrences.
  • After: this branch's ios-maccatalyst job log shows 0 MT7156 occurrences, and the job still succeeds.
  • Both runs show the same 36 IL2026 occurrences (a separate, pre-existing trim-analyzer finding from TodoApp.Uno: trim analysis warnings (IL2026/IL2104/IL2121) on browserwasm/ios/maccatalyst heads #534/fix: suppress IL2026/IL2104/IL2121 trim analysis warnings on TodoApp.Uno browserwasm/ios/maccatalyst #548, out of scope here and unaffected by this change either way) — confirming this fix is scoped precisely to MT7156 and doesn't mask or interact with anything else.
• net10.0-desktop: dotnet restore/build clean, no workload required — confirms the change doesn't regress unrelated heads.
• net10.0-browserwasm: could not verify locally (installing the wasm-tools workload requires elevated privileges in this sandbox, same limitation noted in fix: suppress IL2026/IL2104/IL2121 trim analysis warnings on TodoApp.Uno browserwasm/ios/maccatalyst #548); covered by CI instead (job succeeded, unaffected).
• Root Datasync.Toolkit.sln (unaffected by this change, TodoApp.Uno isn't part of it): restores/builds clean (0 Warning(s), 0 Error(s)). CommunityToolkit.Datasync.Client.Test passes 1432/1432.
• CI: dispatched build-samples.yml on the fork (adrianhall/CommunityToolkit-Datasync, ref issues/541) — all 17 jobs succeeded, including todoapp-uno / ios-maccatalyst and the All samples built aggregation gate. Run: https://github.com/adrianhall/CommunityToolkit-Datasync/actions/runs/29150182538

Not verified locally (relying on CI, same limitation noted in #531/#548):

• ios/maccatalyst: require a full Xcode install (only Command Line Tools available here).
• android: requires the Android SDK/workload.
• windows: requires a Windows runner.