fix: resolve login persistence bug and aggressive logout on network blips

- Updated Login.tsx to automatically redirect users to the dashboard if a valid token is already present in localStorage.

- Refactored getUserById to properly throw server/network errors instead of silently returning undefined.

- Updated AuthGuard in App.tsx to gracefully handle network errors without destroying the user's valid localStorage tokens.

App.tsx

@@ -35,15 +35,27 @@ const AuthGuard: React.FC<{ children: React.ReactNode, roles?: string[] }> = ({
 
       try {
         const fetchedUser = await getUserById(storedUserId);
-        if (fetchedUser && fetchedUser.status === 'active') {
+        if (fetchedUser) {
+          if (fetchedUser.status === 'active') {
             setUser(fetchedUser);
           } else {
+            // User explicitly marked inactive or deleted
+            logout();
+            setUser(null);
+          }
+        } else {
+          // If fetchedUser is undefined but didn't throw, it usually means a 401/403/404 (invalid token or user missing).
+          // However, to be safe against random failures, we should only clear if we are sure it's invalid.
+          // For now, if the token is completely rejected, we log out.
           logout();
           setUser(null);
         }
       } catch (err) {
-        console.error("Auth check failed", err);
-        logout();
+        console.error("Auth check failed (network/server error):", err);
+        // DO NOT logout() here. If the server is offline or restarting, 
+        // we shouldn't wipe the user's local storage tokens.
+        // We just leave the user as null, which will redirect them to login,
+        // but their tokens remain so they can auto-login when the server is back.
         setUser(null);
       } finally {
         setLoading(false);
@@ -53,7 +65,7 @@ const AuthGuard: React.FC<{ children: React.ReactNode, roles?: string[] }> = ({
   }, [location.pathname]);
 
   if (loading) {
-    return <div className="flex h-screen items-center justify-center bg-slate-50 text-slate-400">Carregando...</div>;
+    return <div className="flex h-screen items-center justify-center bg-zinc-50 dark:bg-zinc-950 text-zinc-400">Carregando...</div>;
   }
 
   if (!user) {

pages/Login.tsx

@@ -1,4 +1,4 @@
-import React, { useState } from 'react';
+import React, { useState, useEffect } from 'react';
 import { useNavigate, Link } from 'react-router-dom';
 import { Hexagon, Lock, Mail, ArrowRight, Loader2, Eye, EyeOff, AlertCircle } from 'lucide-react';
 import { login, logout } from '../services/dataService';
@@ -12,6 +12,16 @@ export const Login: React.FC = () => {
   const [error, setError] = useState('');
   const [emailError, setEmailError] = useState('');
 
+  // Auto-redirect if already logged in
+  useEffect(() => {
+    const token = localStorage.getItem('ctms_token');
+    const userId = localStorage.getItem('ctms_user_id');
+    if (token && userId && token !== 'undefined' && token !== 'null') {
+      // Opt to send them to root, AuthGuard will handle role-based routing
+      navigate('/');
+    }
+  }, [navigate]);
+
   const validateEmail = (val: string) => {
     setEmail(val);
     if (!val) {

services/dataService.ts

@@ -280,16 +280,20 @@ export const getUserById = async (id: string): Promise<User | undefined> => {
     const response = await fetch(`${API_URL}/users/${id}`, {
       headers: getHeaders()
     });
-    if (!response.ok) return undefined;
+    if (!response.ok) {
+       if (response.status === 401 || response.status === 403 || response.status === 404) {
+         return undefined; // Invalid user or token
+       }
+       throw new Error(`Server error: ${response.status}`);
+    }
 
     const contentType = response.headers.get("content-type");
     if (contentType && contentType.indexOf("application/json") !== -1) {
       return await response.json();
     }
-    return undefined;
   } catch (error) {
     console.error("API Error (getUserById):", error);
-    return undefined;
+    throw error; // Rethrow so AuthGuard catches it and doesn't wipe tokens
   }
 };