test(selftest): pin v1.5.4 crossfade and quick-picker contracts

ThemeCrossfadeSelfTestStep walks Switch -> crossfade-observed ->
mid-crossfade-switch -> crossfade-end -> restore using
TryGetActiveCrossfade, returns Waiting frame-by-frame and Pass after
the restore concludes. The mid-switch phase fires a second Switch
within ~100ms of the first observed crossfade and asserts the lerped
value is neither identity-from nor identity-to, exercising the
ArmCrossfade mid-flight-origin override.

QuickPickerSelfTestStep verifies the three new resource strings, the
built-in theme floor (>=10), and Config.Tabs non-empty.

HellionChat/Plugin.cs

@@ -330,9 +330,11 @@ public sealed class Plugin : IAsyncDalamudPlugin
 
             SelfTestRegistry.RegisterTestSteps([
                 new SelfTests.ThemeSwitchSelfTestStep(this),
+                new SelfTests.ThemeCrossfadeSelfTestStep(this),
                 new SelfTests.FontManagerCtorSmokeStep(this),
                 new SelfTests.FontPushSmokeStep(this),
                 new SelfTests.WizardStateSmokeStep(this),
+                new SelfTests.QuickPickerSelfTestStep(this),
             ]);
 
             // Re-surface the wizard for existing users when a major UX