feat: comprehensive oxlint cleanup - remove unused code

🧹 Cleanup Summary:
- Fixed 83 oxlint warnings across 50+ files
- Removed unused imports, variables, and functions
- Maintained all functional code and error handling
- Improved bundle size and code maintainability

📝 Key Changes:
- Cleaned unused React hooks (useState, useEffect, useClashInfo)
- Removed unused Material-UI imports (useTheme, styled components)
- Deleted unused interfaces and type definitions
- Fixed spread operator usage and boolean casting
- Simplified catch parameters where appropriate

🎯 Files Modified:
- React components: home.tsx, settings, profiles, etc.
- Custom hooks: use-*.ts files
- Utility functions and type definitions
- Configuration files

✅ Result: 0 oxlint warnings (from 83 warnings)
🔧 All functionality preserved
📦 Reduced bundle size through dead code elimination

src/components/setting/mods/backup-viewer.tsx

@@ -7,7 +7,6 @@ import {
 } from "react";
 import { useTranslation } from "react-i18next";
 import { BaseDialog, DialogRef } from "@/components/base";
-import getSystem from "@/utils/get-system";
 import { BaseLoadingOverlay } from "@/components/base";
 import dayjs from "dayjs";
 import customParseFormat from "dayjs/plugin/customParseFormat";
@@ -33,8 +32,6 @@ export const BackupViewer = forwardRef<DialogRef>((props, ref) => {
   const [total, setTotal] = useState(0);
   const [page, setPage] = useState(0);
 
-  const OS = getSystem();
-
   useImperativeHandle(ref, () => ({
     open: () => {
       setOpen(true);