fix: standardize RunningMode handling between frontend and backend

This commit improves the type consistency between the Rust backend and TypeScript frontend by:

1. Modifying the Rust `get_running_mode()` command to return a String instead of RunningMode enum directly
2. Removing the RunningMode enum and IRunningMode interface from TypeScript types
3. Using string literals for mode comparison in frontend components
4. Standardizing on capitalized mode names (e.g., "Sidecar" instead of "sidecar")

These changes ensure proper serialization/deserialization between backend and frontend,
making the code more maintainable and reducing potential inconsistencies.

src/components/setting/setting-system.tsx

@@ -58,7 +58,7 @@ const SettingSystem = ({ onError }: Props) => {
   }, [autoLaunchEnabled]);
 
   // 是否以sidecar模式运行
-  const isSidecarMode = runningMode === "sidecar";
+  const isSidecarMode = runningMode === "Sidecar";
 
   const sysproxyRef = useRef<DialogRef>(null);
   const tunRef = useRef<DialogRef>(null);