refactor(12.A): rename Mix* visualizer engine to Waveform* abstraction

DeepDrftPublic.Client/Controls/AudioPlayerBar/AudioPlayerBar.razor.cs

@@ -29,7 +29,7 @@ public partial class AudioPlayerBar : ComponentBase, IAsyncDisposable
     // error banner.
     //
     // _miniDock is the minimized FAB container. We observe it in minimized state so
-    // --player-height stays non-zero (the FAB's actual height) and the MixWaveformVisualizer
+    // --player-height stays non-zero (the FAB's actual height) and the WaveformVisualizer
     // clips to the top of the FAB rather than extending to the viewport bottom (fix §1).
     // The player-spacer's .minimized class uses a hardcoded 60px and ignores the var,
     // so publishing the FAB height here does not regress the spacer.
@@ -125,7 +125,7 @@ public partial class AudioPlayerBar : ComponentBase, IAsyncDisposable
         // The Fixed embed is already in normal flow — no spacer/clip needed.
         // For the docked player: we observe in BOTH expanded and minimized states
         // so --player-height always reflects the live height of whichever element
-        // is visible. This keeps the MixWaveformVisualizer clipped to the top of
+        // is visible. This keeps the WaveformVisualizer clipped to the top of
         // the footer in both states (fix §1).
         //   expanded  → observe _playerRoot (full player bar, reflows across breakpoints)
         //   minimized → observe _miniDock   (floating FAB container, ~56–60px)