[Remote rendering 4.5] Remote camera interaction end-to-end

### 📝 Description of the feature

Make rotate, pan, and zoom work against the server-side interactor: the client forwards the interaction event, the server applies it to the camera, renders, and streams the updated frame back. The stock interaction adapter doesn't reliably handle the event format the canvas emits, so a direct dispatch stands in.

Note:

In the spike, the stock vtkRemoteInteractionAdapter.ProcessEvent didn't recognize the JSON event format RemoteCanvas emits, because RemoteCanvas was emitting different event shapes (e.g. both flat {x, y} and nested {position: {x, y}} shapes.
A workaround was used in the spike, dispatching events directly to an interactor instead of going through the adapter, since it wasn't clear whether the adapter's strict behavior is intended or an upstream issue whose fix is to accept both shapes.
If a similar issue is encountered in the course of this user story, we could first check with Kitware on whether we resolve the issue by conforming RemoteCanvas to a single shape or whether the fix is on the adapter side (if it's not intended to be as strict)

### Acceptance Criteria

Rotate, pan, and zoom work in remote mode.

### 💵 Business Value

_No response_

### 🔗 Useful links and references

_No response_

Beginne damit, die Event-Auslösung von RemoteCanvas und den serverseitigen Interactor-Pfad nachzuverfolgen, und untersuche anschließend vtkRemoteInteractionAdapter.ProcessEvent sowie die hier beschriebenen unterschiedlichen JSON-Event-Strukturen. Bestätige das vorgesehene Event-Format oder den Ansatz des direkten Dispatches; abgeschlossen ist die Arbeit, wenn Rotieren, Schwenken und Zoomen im Remote-Modus funktionieren und aktualisierte Frames zurückgestreamt werden.

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