test(app): add headless ViewModel, CLI and localization tests

ViewModels run on Avalonia.Headless: wizard flows, password and file-lock
handling, seed and private-key reveal gating, contacts, settings, sync and
send against the fake server. The CLI entry point is invoked in-process
end to end. Localization checks cover the 7 languages, placeholders and
keys used in sources. Internal seams (UpdateCheck, ProfileOverride) keep
the tests offline.

tests/PalladiumWallet.Tests/Net/LiveServerTests.cs

@@ -13,7 +13,7 @@ namespace PalladiumWallet.Tests.Net;
 ///
 /// Example: PALLADIUM_TEST_SERVERS=1.2.3.4:50002 PALLADIUM_TEST_SSL=1 dotnet test --filter LiveServer
 /// </summary>
-[Collection("Console")] // the probe writes to Console, which is process-global
+[Collection("AppPaths")] // serialized with other tests touching process-wide state (Console, AppPaths)
 public class LiveServerTests
 {
     [Fact]