Add getter methods for response and toolcall in Context

Introduce `Response()` and `ToolCall()` methods to access the respective fields from the `Context` struct. This enhances encapsulation and provides a standardized way to retrieve these values.

context.go

@@ -47,6 +47,14 @@ func (c *Context) Request() Request {
 	return c.request
 }
 
+func (c *Context) Response() *ResponseChoice {
+	return c.response
+}
+
+func (c *Context) ToolCall() *ToolCall {
+	return c.toolcall
+}
+
 func (c *Context) WithContext(ctx context.Context) *Context {
 	return &Context{Context: ctx, request: c.request, response: c.response, toolcall: c.toolcall}
 }