fix: pass params when saving a temporary chat

The system prompt and other chat controls overrides were lost after
saving because `params` wasn't included in the `createNewChat` call.

Author: Algorithm5838

src/lib/components/chat/Chat.svelte

@@ -2730,6 +2730,7 @@
 										id: uuidv4(),
 										title: title.length > 50 ? `${title.slice(0, 50)}...` : title,
 										models: selectedModels,
+										params: params,
 										history: history,
 										messages: messages,
 										timestamp: Date.now()