Improve user data retrieval and add production debugging tools

Update the API to fetch users with simplified logic and introduce detailed SQL scripts and logging for production issue diagnosis.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: a8a78c07-e900-425c-a577-5b4c5894379d
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/a8a78c07-e900-425c-a577-5b4c5894379d/jzCmXCx

production-users-debug.sql

@@ -0,0 +1,37 @@
+-- Script de diagnostic pour résoudre le problème "Aucun utilisateur trouvé" en production
+
+-- 1. Vérifier si la table users existe et contient des données
+SELECT 'Users table check' as diagnostic;
+SELECT COUNT(*) as user_count FROM users;
+SELECT id, username, email, role FROM users LIMIT 5;
+
+-- 2. Vérifier la structure de la table users
+SELECT 'Users table structure' as diagnostic;
+\d users;
+
+-- 3. Vérifier les connexions/permissions de base de données
+SELECT 'Database info' as diagnostic;
+SELECT current_database(), current_user, version();
+
+-- 4. Vérifier la table groups
+SELECT 'Groups table check' as diagnostic;
+SELECT COUNT(*) as group_count FROM groups;
+SELECT id, name FROM groups LIMIT 5;
+
+-- 5. Vérifier la table user_groups et sa structure
+SELECT 'User_groups table check' as diagnostic;
+SELECT COUNT(*) as user_group_count FROM user_groups;
+\d user_groups;
+
+-- 6. Test de la requête utilisée par l'application
+SELECT 'Full user query test' as diagnostic;
+SELECT 
+  u.id,
+  u.username,
+  u.email,
+  u.role,
+  COUNT(ug.group_id) as groups_count
+FROM users u
+LEFT JOIN user_groups ug ON u.id = ug.user_id
+GROUP BY u.id, u.username, u.email, u.role
+LIMIT 5;