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/fixture/fixture.test.ts

@@ -0,0 +1,26 @@
+import { $ } from "bun"
+import { describe, expect, test } from "bun:test"
+import fs from "fs/promises"
+import { tmpdir } from "./fixture"
+
+describe("tmpdir", () => {
+  test("disables fsmonitor for git fixtures", async () => {
+    await using tmp = await tmpdir({ git: true })
+
+    const value = (await $`git config core.fsmonitor`.cwd(tmp.path).quiet().text()).trim()
+    expect(value).toBe("false")
+  })
+
+  test("removes directories on dispose", async () => {
+    const tmp = await tmpdir({ git: true })
+    const dir = tmp.path
+
+    await tmp[Symbol.asyncDispose]()
+
+    const exists = await fs
+      .stat(dir)
+      .then(() => true)
+      .catch(() => false)
+    expect(exists).toBe(false)
+  })
+})