Add support for rendering Canvas component trees in the headless SDK
The headless SDK can fetch structured Custom Elements output from Drupal, but applications cannot render that output without implementing their own tree traversal, component resolution, prop and slot handling, and component registry integration.
### Proposed resolution
Add a content type independent `CanvasComponentTree` renderer for all framework specific adapters.
Generate component implementation registries from discovered local components and update them automatically during development.
Update the example applications to demonstrate the rendering flow.
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