fix(proxy): update live backup when hot-switching provider in proxy mode

When proxy is active, switching providers only updated the database flags
but not the live backup. This caused the wrong provider config to be
restored when stopping the proxy.

Added `update_live_backup_from_provider()` method to ProxyService that
generates backup from provider's settings_config instead of reading from
live files (which are already taken over by proxy).

src-tauri/src/services/proxy.rs

@@ -5,6 +5,7 @@
 use crate::app_config::AppType;
 use crate::config::{get_claude_settings_path, read_json_file, write_json_file};
 use crate::database::Database;
+use crate::provider::Provider;
 use crate::proxy::server::ProxyServer;
 use crate::proxy::types::*;
 use serde_json::{json, Value};
@@ -434,6 +435,49 @@ impl ProxyService {
             .map_err(|e| format!("检查接管状态失败: {e}"))
     }
 
+    /// 从供应商配置更新 Live 备份（用于代理模式下的热切换）
+    ///
+    /// 与 backup_live_configs() 不同，此方法从供应商的 settings_config 生成备份，
+    /// 而不是从 Live 文件读取（因为 Live 文件已被代理接管）。
+    pub async fn update_live_backup_from_provider(
+        &self,
+        app_type: &str,
+        provider: &Provider,
+    ) -> Result<(), String> {
+        let backup_json = match app_type {
+            "claude" => {
+                // Claude: settings_config 直接作为备份
+                serde_json::to_string(&provider.settings_config)
+                    .map_err(|e| format!("序列化 Claude 配置失败: {e}"))?
+            }
+            "codex" => {
+                // Codex: settings_config 包含 {"auth": ..., "config": ...}，直接使用
+                serde_json::to_string(&provider.settings_config)
+                    .map_err(|e| format!("序列化 Codex 配置失败: {e}"))?
+            }
+            "gemini" => {
+                // Gemini: 只提取 env 字段（与原始备份格式一致）
+                // proxy.rs 的 read_gemini_live() 返回 {"env": {...}}
+                let env_backup = if let Some(env) = provider.settings_config.get("env") {
+                    json!({ "env": env })
+                } else {
+                    json!({ "env": {} })
+                };
+                serde_json::to_string(&env_backup)
+                    .map_err(|e| format!("序列化 Gemini 配置失败: {e}"))?
+            }
+            _ => return Err(format!("未知的应用类型: {app_type}")),
+        };
+
+        self.db
+            .save_live_backup(app_type, &backup_json)
+            .await
+            .map_err(|e| format!("更新 {app_type} 备份失败: {e}"))?;
+
+        log::info!("已更新 {app_type} Live 备份（热切换）");
+        Ok(())
+    }
+
     /// 代理模式下切换供应商（热切换，不写 Live）
     pub async fn switch_proxy_target(
         &self,