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/components/EditTournamentForm.tsx

@@ -66,7 +66,7 @@ export default function EditTournamentForm({ tournament }: EditTournamentFormPro
       setTimeout(() => {
         router.push(`/admin/tournaments/${tournament.id}`)
       }, 2000)
-    } catch (err) {
+    } catch {
       setError("An error occurred. Please try again.")
       setIsLoading(false)
     }