fix: use RenderWidget and add animation callback for camera controls

- Change from RenderCanvas to RenderWidget for embedded Qt widget
- Add _animate() callback for canvas.request_draw()
- Update render() to use request_draw() for continuous rendering
- This enables OrbitController to work properly with mouse events

src/fluency/rendering/pygfx_renderer.py

@@ -92,10 +92,10 @@ class PygfxRenderer(Renderer):
         """Initialize pygfx with Qt widget."""
         try:
             import pygfx as gfx
-            from rendercanvas.qt import RenderCanvas
+            from rendercanvas.qt import RenderWidget
             from PySide6.QtWidgets import QVBoxLayout
 
-            self._canvas = RenderCanvas(parent=parent_widget)
+            self._canvas = RenderWidget(parent=parent_widget)
             self._renderer = gfx.renderers.WgpuRenderer(self._canvas)
             self._scene = gfx.Scene()
 
@@ -112,6 +112,8 @@ class PygfxRenderer(Renderer):
             layout.setContentsMargins(0, 0, 0, 0)
             layout.addWidget(self._canvas)
 
+            self._canvas.request_draw(self._animate)
+
             self._setup_picking()
             self._initialized = True
 
@@ -124,6 +126,11 @@ class PygfxRenderer(Renderer):
             traceback.print_exc()
             return False
 
+    def _animate(self):
+        """Animation callback for the canvas."""
+        if self._initialized:
+            self._renderer.render(self._scene, self._camera)
+
     def _setup_lighting(self) -> None:
         """Setup scene lighting."""
         import pygfx as gfx
@@ -394,7 +401,6 @@ class PygfxRenderer(Renderer):
     def render(self) -> None:
         """Trigger a render."""
         if self._initialized:
-            self._renderer.render(self._scene, self._camera)
             self._canvas.request_draw()
 
     def on_pick(self, callback: Callable[[Any], None]) -> None: