feat(deepseek): 添加 DeepSeek reasoning 模式支持

src/config/mod.rs

@@ -110,6 +110,10 @@ pub struct LlmConfig {
     /// API key (stored in config for fallback, encrypted if encrypt_sensitive is true)
     #[serde(default)]
     pub api_key: Option<String>,
+
+    /// Enable thinking/reasoning mode (deepseek, kimi)
+    #[serde(default)]
+    pub thinking_enabled: bool,
 }
 
 fn default_api_key_storage() -> String {
@@ -127,6 +131,7 @@ impl Default for LlmConfig {
             timeout: default_timeout(),
             api_key_storage: default_api_key_storage(),
             api_key: None,
+            thinking_enabled: false,
         }
     }
 }