Store user agent in conversation (#940)

* Store user agent on conversation creation

* casing header

src/lib/types/Conversation.ts

@@ -23,4 +23,6 @@ export interface Conversation extends Timestamps {
 
 	preprompt?: string;
 	assistantId?: Assistant["_id"];
+
+	userAgent?: string;
 }

src/routes/conversation/+server.ts

@@ -105,6 +105,7 @@ export const POST: RequestHandler = async ({ locals, request }) => {
 		assistantId: values.assistantId ? new ObjectId(values.assistantId) : undefined,
 		createdAt: new Date(),
 		updatedAt: new Date(),
+		userAgent: request.headers.get("User-Agent") ?? undefined,
 		embeddingModel,
 		...(locals.user ? { userId: locals.user._id } : { sessionId: locals.sessionId }),
 		...(values.fromShare ? { meta: { fromShareId: values.fromShare } } : {}),