fix(core): copilot client should throw right ai error (#9958)

[BS-2488](https://linear.app/affine-design/issue/BS-2488/copilot-client-需要正确返回错误类型)

blocksuite/blocks/src/root-block/widgets/ai-panel/components/state/error.ts

@@ -155,7 +155,7 @@ export class AIPanelError extends WithDisposable(LitElement) {
                   <span>Cancel</span>
                 </div>
                 <div @click=${this.config.login} class="action-button primary">
-                  <span>login</span>
+                  <span>Login</span>
                 </div>
               </div>`,
         ],