Description

In chat POC, added gating on scrollToBottom to prevent scrolling to bottom on whether or not user is already at bottom of chat window, or jumps there explicitly. Without a fix like this, reading what the LLM has produced requires waiting until it's done responding, since any vertical update will try to also update scroll to bottom.

Testing

• Open POC chat window (Harbor > Quick Actions > Open Chat)
• Ask LLM to generate a haiku for every letter of the alphabet (enough vertical scroll)
• While LLM response is being generated, scroll chat window to verify that response continues without moving scroll
• Click on "Jump to latest message" button to confirm that chat returns to bottom if scroll isn't already there
• Generate again and clear chat window during generation to confirm that state resets

Checklist

• Tests pass (cargo test, npm test)
• Code formatted (cargo fmt)
• Extension loads without errors
• Documentation updated (if applicable)