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/model.test.ts

@@ -0,0 +1,23 @@
+import { describe, expect, test } from "bun:test"
+import { Schema } from "effect"
+import { ModelV2 } from "@opencode-ai/core/model"
+import { ProviderV2 } from "@opencode-ai/core/provider"
+
+const decode = Schema.decodeUnknownSync(ModelV2.Ref)
+
+describe("ModelV2.Ref", () => {
+  test("accepts a model selection without a variant", () => {
+    expect(decode({ id: "claude-sonnet", providerID: "anthropic" })).toEqual({
+      id: ModelV2.ID.make("claude-sonnet"),
+      providerID: ProviderV2.ID.make("anthropic"),
+    })
+  })
+
+  test("preserves an explicit model variant", () => {
+    expect(decode({ id: "claude-sonnet", providerID: "anthropic", variant: "high" })).toEqual({
+      id: ModelV2.ID.make("claude-sonnet"),
+      providerID: ProviderV2.ID.make("anthropic"),
+      variant: ModelV2.VariantID.make("high"),
+    })
+  })
+})