feat: 品牌替换 + 启动优化 + AGENTS.md 模板定制

- 品牌替换：OpenCode/opencode → AirCoding/aircoding（16+ 文件）
- Logo ASCII art：修复 left/right 行数不匹配导致的启动崩溃
- 启动诊断：添加 OPENCODE_PRINT_TIMING 计时探针
- dev 模式默认 --pure 跳过外部插件加载
- AGENTS.md 模板：追加 AirCoding 多 Agent 专项段落
- architect prompt + plugin：强化 AGENTS.md 产出验证

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)
+  })
+})