Delegate live updates to view elements

[samuel-williams-shopify]

Summary

• add synchronous ViewElement#morph(fragment, options) with morphdom as the default implementation
• delegate Live.update() to any target implementing morph(), while retaining direct morphdom fallback for ordinary elements
• preserve existing immediate reply and dispatcher behavior
• document update ownership, nested light-DOM reconciliation, stable ID matching, and Shadow DOM boundaries
• test custom morph delegation and ordinary-element fallback

Validation

• npm test
• npm pack --dry-run
• git diff --check