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/desktop/icons/README.md

@@ -0,0 +1,14 @@
+# Tauri Icons
+
+Here's the process I've been using to create icons:
+
+- Save source image as `app-icon.png` in `packages/desktop`
+- `cd` to `packages/desktop`
+- Run `bun tauri icon -o src-tauri/icons/{environment}`
+- Use [Image2Icon](https://img2icnsapp.com/)'s 'Big Sur Icon' preset to generate an `icon.icns` file and place it in the appropriate icons folder
+
+The Image2Icon step is necessary as the `icon.icns` generated by `app-icon.png` does not apply the shadow/padding expected by macOS,
+so app icons appear larger than expected.
+
+For unpackaged Electron on macOS, `app.dock.setIcon()` should use a PNG. Keep `dock.png` in each channel folder synced with the
+extracted `icon_128x128@2x.png` from that channel's `icon.icns` so the dev Dock icon matches the packaged app inset.