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/docs/essentials/navigation.mdx

@@ -0,0 +1,87 @@
+---
+title: "Navigation"
+description: "The navigation field in docs.json defines the pages that go in the navigation menu"
+icon: "map"
+---
+
+The navigation menu is the list of links on every website.
+
+You will likely update `docs.json` every time you add a new page. Pages do not show up automatically.
+
+## Navigation syntax
+
+Our navigation syntax is recursive which means you can make nested navigation groups. You don't need to include `.mdx` in page names.
+
+<CodeGroup>
+
+```json Regular Navigation
+"navigation": {
+  "tabs": [
+    {
+      "tab": "Docs",
+      "groups": [
+        {
+          "group": "Getting Started",
+          "pages": ["quickstart"]
+        }
+      ]
+    }
+  ]
+}
+```
+
+```json Nested Navigation
+"navigation": {
+  "tabs": [
+    {
+      "tab": "Docs",
+      "groups": [
+        {
+          "group": "Getting Started",
+          "pages": [
+            "quickstart",
+            {
+              "group": "Nested Reference Pages",
+              "pages": ["nested-reference-page"]
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}
+```
+
+</CodeGroup>
+
+## Folders
+
+Simply put your MDX files in folders and update the paths in `docs.json`.
+
+For example, to have a page at `https://yoursite.com/your-folder/your-page` you would make a folder called `your-folder` containing an MDX file called `your-page.mdx`.
+
+<Warning>
+
+You cannot use `api` for the name of a folder unless you nest it inside another folder. Mintlify uses Next.js which reserves the top-level `api` folder for internal server calls. A folder name such as `api-reference` would be accepted.
+
+</Warning>
+
+```json Navigation With Folder
+"navigation": {
+  "tabs": [
+    {
+      "tab": "Docs",
+      "groups": [
+        {
+          "group": "Group Name",
+          "pages": ["your-folder/your-page"]
+        }
+      ]
+    }
+  ]
+}
+```
+
+## Hidden pages
+
+MDX files not included in `docs.json` will not show up in the sidebar but are accessible through the search bar and by linking directly to them.