fix: resolve frontend lint errors and cleanup types

frontend/src/auth/auth.ts

@@ -47,14 +47,14 @@ export const { handlers, signIn, signOut, auth } = NextAuth({
     async jwt({ token, account }) {
       if (account && account.access_token) {
         // Add clubs claim from Keycloak access token
-        token.clubs = (account as any).clubs as Record<string, string> || {}
-        token.accessToken = account.access_token as string
+        token.clubs = (account as { clubs?: Record<string, string> }).clubs || {}
+        token.accessToken = account.access_token
         
         try {
           const payload = JSON.parse(Buffer.from((token.accessToken as string).split('.')[1], 'base64').toString());
-          const roles = payload.realm_access?.roles || [];
+          const roles = (payload.realm_access?.roles as string[]) || [];
           token.isAdmin = roles.includes('admin');
-        } catch (e) {
+        } catch {
           token.isAdmin = false;
         }
       }
@@ -63,10 +63,10 @@ export const { handlers, signIn, signOut, auth } = NextAuth({
     async session({ session, token }) {
       // Expose clubs to client
       if (session.user) {
-        session.user.clubs = (token as any).clubs as Record<string, string> | undefined
-        session.user.isAdmin = (token as any).isAdmin as boolean | undefined
+        session.user.clubs = token.clubs as Record<string, string> | undefined
+        session.user.isAdmin = token.isAdmin as boolean | undefined
       }
-      session.accessToken = (token as any).accessToken as string | undefined
+      session.accessToken = token.accessToken as string | undefined
       return session
     }
   }