fix: improve error handling and type safety

- Replaced 'any' types with proper TypeScript types
- Improved error handling with instanceof checks
- Removed unused imports (calculateExpectedTeamScore)
- Updated error messages to be more descriptive
- Removed deprecated eslint.config.mjs file

src/app/auth/login/page.tsx

@@ -32,7 +32,7 @@ export default function LoginPage() {
         // Navigate to admin page - Better Auth will handle session update
         router.push("/admin")
       }
-    } catch (err) {
+    } catch {
       setError("An unexpected error occurred")
     } finally {
       setLoading(false)