docs(ai-outfit): add ai_models.json sample (placeholder keys)

Template covering all four api_type variants (chat/gemini/images/images_edits).
Copy to ~/.cmbot/config/ai_models.json and fill real values; the real file
(with keys) stays out of git.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/ai_models.sample.json

@@ -0,0 +1,45 @@
+{
+  "_说明": "复制此文件到 ~/.cmbot/config/ai_models.json（Windows: %USERPROFILE%\\.cmbot\\config\\ai_models.json），把 api_key/url/model 换成真实值。含真实 key 的 ai_models.json 不要提交 git。界面「AI 模型」下拉显示每项的 name；下面列了 4 种 api_type 示例，按你的中转接口选一种保留即可，其余可删。",
+  "models": [
+    {
+      "name": "Nano Banana · 中转(chat)",
+      "url": "https://your-relay.example.com/v1/chat/completions",
+      "model": "nano-banana",
+      "api_key": "sk-REPLACE_WITH_YOUR_KEY",
+      "api_type": "chat",
+      "timeout_seconds": 0,
+      "connect_timeout_seconds": 30,
+      "extra_body": {}
+    },
+    {
+      "name": "Gemini 图像 · 中转(gemini)",
+      "url": "https://your-relay.example.com/v1beta/models/{model}:generateContent",
+      "model": "gemini-2.5-flash-image",
+      "api_key": "sk-REPLACE_WITH_YOUR_KEY",
+      "api_type": "gemini",
+      "timeout_seconds": 0,
+      "connect_timeout_seconds": 30,
+      "extra_body": {}
+    },
+    {
+      "name": "Images 生成 · 中转(images)",
+      "url": "https://your-relay.example.com/v1/images/generations",
+      "model": "your-image-model",
+      "api_key": "sk-REPLACE_WITH_YOUR_KEY",
+      "api_type": "images",
+      "timeout_seconds": 0,
+      "connect_timeout_seconds": 30,
+      "extra_body": {}
+    },
+    {
+      "name": "Images 编辑 · 中转(images_edits)",
+      "url": "https://your-relay.example.com/v1/images/edits",
+      "model": "your-edit-model",
+      "api_key": "sk-REPLACE_WITH_YOUR_KEY",
+      "api_type": "images_edits",
+      "timeout_seconds": 0,
+      "connect_timeout_seconds": 30,
+      "extra_body": {}
+    }
+  ]
+}