merge: resolve conflicts from origin/dev into PR #1495

- Use PR branch (dev-nofxi) as authority for agent/ module code
- Merge dev's newer model names (MiniMax-M2.7, deepseek-v4-flash)
  with PR's blockrun provider entries
- Fix duplicate agent init in main.go, keep defer-based Stop()
- Fix var type bug in store/ai_model.go (model → models)
- Remove dev-only test files incompatible with PR's evolved agent code
  (to be re-synced after merge)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/i18n/zh-CN/README.md

@@ -47,6 +47,20 @@ curl -fsSL https://raw.githubusercontent.com/NoFxAiOS/nofx/main/install.sh | bas
 
 ---
 
+## 快速演示
+
+<p align="center">
+  <a href="https://drive.google.com/file/d/1frzw-HDZ3viQvLOQKsAJGc9bT0dXs68D/view">
+    <img src="../../../screenshots/demo-cover.png" alt="NOFX 快速演示视频" width="900"/>
+  </a>
+</p>
+
+<p align="center">
+  点击封面图即可观看 Demo 视频。
+</p>
+
+---
+
 ## x402 如何工作
 
 传统流程：注册账号 → 购买额度 → 获取 API Key → 管理配额 → 轮换密钥。