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/util/error.test.ts

@@ -0,0 +1,16 @@
+import { describe, expect, test } from "bun:test"
+import { NamedError } from "@opencode-ai/core/util/error"
+import { MessageError } from "../../src/session/message-error"
+
+describe("util.error", () => {
+  test("schema-backed named errors are real NamedError instances", () => {
+    const error = new MessageError.AuthError({ providerID: "anthropic", message: "boom" })
+
+    expect(error).toBeInstanceOf(NamedError)
+    expect(error.toObject()).toEqual({ name: "ProviderAuthError", data: { providerID: "anthropic", message: "boom" } })
+  })
+
+  test("named errors without fields serialize data", () => {
+    expect(new MessageError.OutputLengthError({}).toObject()).toEqual({ name: "MessageOutputLengthError", data: {} })
+  })
+})