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/lib/auth-simple.ts

@@ -45,11 +45,11 @@ export type AuthUser = {
     email: string;
     name?: string;
     role?: string;
-    [key: string]: any;
+    [key: string]: unknown;
   };
   session: {
     token: string;
     expiresAt: Date;
-    [key: string]: any;
+    [key: string]: unknown;
   };
 } | null;