Class RealtimeChannelPaneComponent

Generic host for an interactive channel's surface on the call overlay's stage. Given the per-session channel Plugin, it:

1. dynamically creates the plugin's surface component (BaseRealtimeChannelClient.GetSurfaceComponent) into its own view container;
2. immediately hands the created instance to BaseRealtimeChannelClient.BindSurface — synchronously, BEFORE the surface's first change detection, so inputs the plugin sets are visible in its ngOnInit;
3. tells the plugin whether the surface is on screen (BaseRealtimeChannelClient.OnSurfaceVisibilityChange) and where it is placed (BaseRealtimeChannelClient.OnSurfacePlacementChange) right after binding and whenever Visible or Placement changes;
4. notifies BaseRealtimeChannelClient.UnbindSurface when the pane is destroyed (the channel left the session / the overlay was torn down) or handed another plugin, flipping the plugin back into its no-surface tool-execution mode.

This is how channel surfaces render with ZERO channel-specific wiring in the overlay: the host never knows the surface component's type or API — the plugin wires its own inputs/outputs in BindSurface.

The created component is inserted as a SIBLING of this host element (standard ViewContainerRef semantics), so it participates directly in its container's layout; the host element itself renders nothing (display: none).