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/opencode/test/plugin/openai-rollout.test.ts

@@ -0,0 +1,17 @@
+import { describe, expect, test } from "bun:test"
+import { experimentalWebSocketsEnabled } from "../../src/plugin"
+
+describe("plugin.openai.websocket rollout", () => {
+  test("enables websockets by default only on pre-release channels", () => {
+    expect(experimentalWebSocketsEnabled({ enabled: false, channel: "local" })).toBe(true)
+    expect(experimentalWebSocketsEnabled({ enabled: false, channel: "dev" })).toBe(true)
+    expect(experimentalWebSocketsEnabled({ enabled: false, channel: "beta" })).toBe(true)
+    expect(experimentalWebSocketsEnabled({ enabled: false, channel: "latest" })).toBe(false)
+    expect(experimentalWebSocketsEnabled({ enabled: false, channel: "prod" })).toBe(false)
+  })
+
+  test("allows releases to opt in through the experimental flag", () => {
+    expect(experimentalWebSocketsEnabled({ enabled: true, channel: "latest" })).toBe(true)
+    expect(experimentalWebSocketsEnabled({ enabled: true, channel: "prod" })).toBe(true)
+  })
+})