Text selection loss during incremental AI updates

[examan]

Currently, morphdom updates Text nodes by directly replacing the entire nodeValue:

if (morphedNode.nodeValue !== toNode.nodeValue) {
    morphedNode.nodeValue = toNode.nodeValue;
}

When working with AI-generated content, text typically grows incrementally as responses are generated. The current direct replacement approach causes any existing text selection to be lost, disrupting user interaction with the content.