fix: 修正 logo 中 N 和 G 字母造型

N 添加对角线笔画（█▄ █），G 添加内横杠（█ ▀█），
避免与 O 字母造型雷同。同步更新 ui.ts 中的硬编码 wordmark。

packages/llm/src/providers/xai.ts

@@ -0,0 +1,56 @@
+import { AuthOptions, type ProviderAuthOption } from "../route/auth-options"
+import type { RouteDefaultsInput } from "../route/client"
+import { ProviderID, type ModelID } from "../schema"
+import * as OpenAICompatibleProfiles from "./openai-compatible-profile"
+import * as OpenAICompatibleChat from "../protocols/openai-compatible-chat"
+import * as OpenAIResponses from "../protocols/openai-responses"
+
+export const id = ProviderID.make("xai")
+
+export type ModelOptions = RouteDefaultsInput &
+  ProviderAuthOption<"optional"> & {
+    readonly baseURL?: string
+  }
+
+export const routes = [OpenAIResponses.route, OpenAICompatibleChat.route]
+
+const auth = (options: ProviderAuthOption<"optional">) => AuthOptions.bearer(options, "XAI_API_KEY")
+
+const configuredResponsesRoute = (input: ModelOptions) => {
+  const { apiKey: _, auth: _auth, baseURL, ...rest } = input
+  return OpenAIResponses.route.with({
+    ...rest,
+    provider: id,
+    endpoint: { baseURL: baseURL ?? OpenAICompatibleProfiles.profiles.xai.baseURL },
+    auth: auth(input),
+  })
+}
+
+const configuredChatRoute = (input: ModelOptions) => {
+  const { apiKey: _, auth: _auth, baseURL, ...rest } = input
+  return OpenAICompatibleChat.route.with({
+    ...rest,
+    provider: id,
+    endpoint: { baseURL: baseURL ?? OpenAICompatibleProfiles.profiles.xai.baseURL },
+    auth: auth(input),
+  })
+}
+
+export const configure = (input: ModelOptions = {}) => {
+  const responsesRoute = configuredResponsesRoute(input)
+  const chatRoute = configuredChatRoute(input)
+  const responses = (modelID: string | ModelID) => responsesRoute.model({ id: modelID })
+  const chat = (modelID: string | ModelID) => chatRoute.model({ id: modelID })
+  return {
+    id,
+    model: responses,
+    responses,
+    chat,
+    configure,
+  }
+}
+
+export const provider = configure()
+export const model = provider.model
+export const responses = provider.responses
+export const chat = provider.chat