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/tui/test/fixture/tui-plugin.ts

@@ -0,0 +1,36 @@
+import type { TuiPluginApi } from "@opencode-ai/plugin/tui"
+import { RGBA } from "@opentui/core"
+import { createTuiResolvedConfig } from "./tui-runtime"
+
+type Opts = {
+  client?: TuiPluginApi["client"]
+  keymap?: TuiPluginApi["keymap"]
+  attention?: Partial<TuiPluginApi["attention"]>
+  event?: TuiPluginApi["event"]
+  state?: { session?: Partial<TuiPluginApi["state"]["session"]> }
+}
+
+export function createTuiPluginApi(opts: Opts = {}) {
+  const values = new Map<string, unknown>()
+  const color = RGBA.fromInts(200, 200, 200)
+  const dialog = { clear() {}, replace() {}, setSize() {}, size: "medium" as const, depth: 0, open: false }
+  return {
+    attention: { notify: async () => ({ ok: false, notification: false, sound: false }), ...opts.attention },
+    client: opts.client,
+    event: opts.event,
+    keymap: opts.keymap,
+    kv: {
+      get(name: string, fallback?: unknown) {
+        return values.has(name) ? values.get(name) : fallback
+      },
+      set(name: string, value: unknown) {
+        values.set(name, value)
+      },
+      ready: true,
+    },
+    state: { session: { get: () => undefined, ...opts.state?.session } },
+    theme: { current: new Proxy({}, { get: () => color }) },
+    tuiConfig: createTuiResolvedConfig(),
+    ui: { dialog },
+  } as unknown as TuiPluginApi
+}