feat(auth): enhance logging for JWT and session handling in auth callbacks

frontend/auth.ts

@@ -42,11 +42,28 @@ export const { handlers, auth, signIn, signOut } = NextAuth({
         token.userId = Number(user.id);
         token.username = user.name ?? '';
         token.role = (user as any).role as string;
+        // eslint-disable-next-line no-console
+        console.log('[NextAuth JWT callback] Token set:', {
+          hasAccessToken: !!token.accessToken,
+          role: token.role,
+          username: token.username,
+        });
       }
       return token;
     },
     session({ session, token }) {
-      session.accessToken = token.accessToken as string;
+      // eslint-disable-next-line no-console
+      console.log('[NextAuth session callback] Token data:', {
+        tokenAccessToken: token.accessToken,
+        tokenRole: token.role,
+        tokenUserId: token.userId,
+      });
+      if (token.accessToken) {
+        session.accessToken = token.accessToken as string;
+      } else {
+        // eslint-disable-next-line no-console
+        console.warn('[NextAuth session callback] WARNING: No accessToken in token!');
+      }
       session.user.id = String(token.userId);
       session.user.name = token.username as string;
       (session.user as any).role = token.role as string;