refactor(audience-sample): centralise status messages in SampleAppUi.Messages

AudienceSample.cs had inline status strings at every RunAndLog "Ok"
return and AppendLog call (SDK stopped, anonymous ID regenerated
queue cleared, queue flushed, erasure request dispatched, backend
acknowledged, plus two interpolated messages for track-dropped and
flushInterval-clamped warnings).

Adds five plain-string constants and two format-string constants
(suffixed Fmt, used with string.Format) to the existing
SampleAppUi.Messages catalogue alongside the consent-flow messages
already centralised there. Migrates seven inline references in
AudienceSample.cs.

The two interpolated status strings used em-dashes; replaced with
commas in the centralised form to match the project glyph rule.
NoActiveIdentity (already in Messages) had the same em-dash
artefact and gets the same comma replacement.

Per the user's "everything random goes in a constant" stance.

Follow-up to SDK-272 (centralisation of duplicated literals).

Author: ImmutableJeffrey

examples/audience/Assets/SampleApp/Scripts/AudienceSample.cs

@@ -71,30 +71,30 @@ private void OnShutdown() => RunAndLog(SampleAppUi.LogLabels.Shutdown, () =>
             _initialised = false;
             ResetIdentityMirror();
             OnSdkStateChanged();
-            return "SDK stopped";
+            return SampleAppUi.Messages.SdkStopped;
         });
 
         private void OnReset() => RunAndLog(SampleAppUi.LogLabels.Reset, () =>
         {
             ImmutableAudience.Reset();
             ResetIdentityMirror();
             OnSdkStateChanged();
-            return "anonymous ID regenerated, queue cleared";
+            return SampleAppUi.Messages.AnonymousIdRegeneratedQueueCleared;
         });
 
         private async Task OnFlushAsync()
         {
-            try { await ImmutableAudience.FlushAsync(); AppendLog(SampleAppUi.LogLabels.Flush, "queue flushed", LogLevel.Ok, LogSource.App); OnSdkStateChanged(); }
+            try { await ImmutableAudience.FlushAsync(); AppendLog(SampleAppUi.LogLabels.Flush, SampleAppUi.Messages.QueueFlushed, LogLevel.Ok, LogSource.App); OnSdkStateChanged(); }
             catch (Exception ex) { AppendLog(SampleAppUi.LogLabels.Flush, ex.Message, LogLevel.Err, LogSource.App); }
         }
 
         private async Task OnDeleteDataAsync()
         {
-            AppendLog(SampleAppUi.LogLabels.DeleteData, "erasure request dispatched", LogLevel.Info, LogSource.App);
+            AppendLog(SampleAppUi.LogLabels.DeleteData, SampleAppUi.Messages.ErasureRequestDispatched, LogLevel.Info, LogSource.App);
             try
             {
                 await ImmutableAudience.DeleteData();
-                AppendLog(SampleAppUi.LogLabels.DeleteData, "backend acknowledged", LogLevel.Ok, LogSource.App);
+                AppendLog(SampleAppUi.LogLabels.DeleteData, SampleAppUi.Messages.BackendAcknowledged, LogLevel.Ok, LogSource.App);
             }
             catch (Exception ex)
             {
@@ -288,7 +288,7 @@ private static void GuardConsentForTrack()
             var consent = ImmutableAudience.CurrentConsent;
             if (!consent.CanTrack())
                 throw new InvalidOperationException(
-                    $"track dropped — consent is {consent.ToLowercaseString()}; raise to anonymous or full to queue events");
+                    string.Format(SampleAppUi.Messages.TrackDroppedConsentFmt, consent.ToLowercaseString()));
         }
 
         // Refresh* are idempotent reads, so calling all four every time is
@@ -320,7 +320,7 @@ private AudienceConfig BuildAudienceConfig(InitForm form, Action<AudienceError>
             if (form.FlushIntervalMs is int flushMs && flushMs > 0)
             {
                 if (flushMs < 1000)
-                    AppendLog(SampleAppUi.LogLabels.Init, $"flushInterval {flushMs}ms below 1s — clamped", LogLevel.Warn, LogSource.App);
+                    AppendLog(SampleAppUi.LogLabels.Init, string.Format(SampleAppUi.Messages.FlushIntervalBelowOneSecondClampedFmt, flushMs), LogLevel.Warn, LogSource.App);
                 config.FlushIntervalSeconds = Math.Max(1, flushMs / 1000);
             }
             if (form.FlushSize is int flushSize && flushSize > 0)

examples/audience/Assets/SampleApp/Scripts/SampleAppUi.cs

@@ -182,9 +182,22 @@ internal static class Messages
             internal const string QueueStartedSessionCreated = "queue started, session created";
             internal const string QueuePurgedAnonymousIdCleared = "queue purged, anonymous ID cleared";
             internal const string UserIdCleared = "userId cleared";
-            internal const string NoActiveIdentity = "no active identity — call Identify first";
+            internal const string NoActiveIdentity = "no active identity, call Identify first";
             internal const string TraitsRequired = "traits required";
             internal const string Ready = "Sample app loaded. Paste a publishable key and click Init.";
+
+            // Status messages emitted by AudienceSample's RunAndLog handlers.
+            internal const string SdkStopped = "SDK stopped";
+            internal const string AnonymousIdRegeneratedQueueCleared = "anonymous ID regenerated, queue cleared";
+            internal const string QueueFlushed = "queue flushed";
+            internal const string ErasureRequestDispatched = "erasure request dispatched";
+            internal const string BackendAcknowledged = "backend acknowledged";
+
+            // Formatted variants for use with string.Format or interpolation.
+            internal const string TrackDroppedConsentFmt =
+                "track dropped, consent is {0}; raise to anonymous or full to queue events";
+            internal const string FlushIntervalBelowOneSecondClampedFmt =
+                "flushInterval {0}ms below 1s, clamped";
         }
 
         // Mirrors AudienceSample.UI.cs PopulateTypedEventAccordions naming: