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

.github/workflows/notify-discord.yml

@@ -0,0 +1,14 @@
+name: notify-discord
+
+on:
+  release:
+    types: [released] # fires when a draft release is published
+
+jobs:
+  notify:
+    runs-on: blacksmith-4vcpu-ubuntu-2404
+    steps:
+      - name: Send nicely-formatted embed to Discord
+        uses: SethCohen/github-releases-to-discord@24d166886aee4646d448c8a389ff9e1ebcab3682 # v1.20.0
+        with:
+          webhook_url: ${{ secrets.DISCORD_WEBHOOK }}