docs(schema,config): clarify reasoning_effort semantics for MiMo thinking mode

- Update AgentDefaults.reasoning_effort comment to document "none"
  (disable) and None (preserve provider default).
- Add configuration.md tip explaining MiMo thinking mode behavior.

docs/configuration.md

@@ -53,6 +53,7 @@ IMAP_PASSWORD=your-password-here
 > - **Zhipu Coding Plan**: If you're on Zhipu's coding plan, set `"apiBase": "https://open.bigmodel.cn/api/coding/paas/v4"` in your zhipu provider config.
 > - **Alibaba Cloud BaiLian**: If you're using Alibaba Cloud BaiLian's OpenAI-compatible endpoint, set `"apiBase": "https://dashscope.aliyuncs.com/compatible-mode/v1"` in your dashscope provider config.
 > - **Step Fun (Mainland China)**: If your API key is from Step Fun's mainland China platform (stepfun.com), set `"apiBase": "https://api.stepfun.com/v1"` in your stepfun provider config.
+> - **Xiaomi MiMo thinking mode**: MiMo models (e.g. `mimo-v2.5-pro`) default to enabled thinking. Use `agents.defaults.reasoningEffort: "none"` to disable it, or `"low"` / `"medium"` / `"high"` to keep it on. Omitting the field preserves the provider's per-model default.
 
 | Provider | Purpose | Get API Key |
 |----------|---------|-------------|

nanobot/config/schema.py

@@ -88,7 +88,7 @@ class AgentDefaults(Base):
         validation_alias=AliasChoices("toolHintMaxLength"),
         serialization_alias="toolHintMaxLength",
     )  # Max characters for tool hint display (e.g. "$ cd …/project && npm test")
-    reasoning_effort: str | None = None  # low / medium / high / adaptive - enables LLM thinking mode
+    reasoning_effort: str | None = None  # low / medium / high / adaptive / none — LLM thinking effort; None preserves the provider default
     timezone: str = "UTC"  # IANA timezone, e.g. "Asia/Shanghai", "America/New_York"
     bot_name: str = "nanobot"  # Display name shown in CLI prompts (e.g. "{name} is thinking...")
     bot_icon: str = "🐈"  # Short icon (emoji or text) shown next to the bot name in CLI; "" to omit