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/clipboard.test.ts

@@ -0,0 +1,19 @@
+import { expect, test } from "bun:test"
+import { copyCommand } from "../src/clipboard"
+
+test("prefers Wayland clipboard when available", () => {
+  expect(copyCommand("linux", true, (name) => name === "wl-copy")).toEqual(["wl-copy"])
+})
+
+test("uses osascript on macOS", () => {
+  expect(copyCommand("darwin", false, (name) => name === "osascript")).toEqual(["osascript"])
+})
+
+test("falls back through X11 clipboard commands", () => {
+  expect(copyCommand("linux", true, (name) => name === "xclip")).toEqual(["xclip", "-selection", "clipboard"])
+  expect(copyCommand("linux", false, (name) => name === "xsel")).toEqual(["xsel", "--clipboard", "--input"])
+})
+
+test("returns undefined when native clipboard is unavailable", () => {
+  expect(copyCommand("linux", false, () => false)).toBeUndefined()
+})