Added type definitions for Message, Model, and Conversation.

src/lib/types/index.d.ts

@@ -0,0 +1,17 @@
+type Message = {
+	role: string;
+	content: string;
+};
+
+type Model = {
+	model: string;
+	temperature: number;
+	maxTokens: number;
+	streaming: boolean;
+	jsonMode: boolean;
+};
+
+type Conversation = {
+	model: Model;
+	messages: Message[];
+};