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/core/test/fixture/location.ts

@@ -0,0 +1,12 @@
+import { Location } from "@opencode-ai/core/location"
+import { Project } from "@opencode-ai/core/project"
+import { AbsolutePath } from "@opencode-ai/core/schema"
+
+export function location(ref: Location.Ref, input: { projectDirectory?: AbsolutePath; vcs?: Project.Vcs } = {}) {
+  return {
+    directory: ref.directory,
+    workspaceID: ref.workspaceID,
+    project: { id: Project.ID.global, directory: input.projectDirectory ?? ref.directory },
+    vcs: input.vcs,
+  } satisfies Location.Interface
+}