fix(audience-session): Log.Debug breadcrumb on double-Pause

The double-Pause guard silently returned. A studio seeing unexpected
engagement numbers had no way to confirm a spurious lifecycle-bridge
Pause was the cause.

Log.Debug (gated by config.Debug) surfaces the event during integration
without spamming production logs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ImmutableJeffrey

src/Packages/Audience/Runtime/Core/Session.cs

@@ -122,7 +122,11 @@ internal void Pause()
                 // Keep the original anchor. Shifting forward shrinks Resume's
                 // pauseDuration (and ComputeEngagedSecondsLocked's live pause
                 // when End fires while paused), over-crediting engagement.
-                if (_pausedAt.HasValue) return;
+                if (_pausedAt.HasValue)
+                {
+                    Log.Debug("Session: Pause while already paused — ignoring.");
+                    return;
+                }
                 _pausedAt = _getUtcNow();
             }
         }