chore: remove SonarQube stages from Jenkins pipeline

- Remove SonarQube Analysis stage
- Remove Quality Gate stage
- Keep configuration files for future use (sonar-project.properties, .sonarignore)

The SonarQube integration requires additional Jenkins plugin configuration.
Configuration files are preserved for when the plugin is properly set up.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Jenkinsfile

@@ -81,32 +81,6 @@ pipeline {
             }
         }
 
-        stage('SonarQube Analysis') {
-            agent {
-                docker {
-                    image 'sonarsource/sonar-scanner-cli:latest'
-                    args '-u root'
-                }
-            }
-            steps {
-                echo "🔍 Analyse de la qualité du code avec SonarQube..."
-                script {
-                    withSonarQubeEnv('SonarQube') {
-                        sh 'sonar-scanner'
-                    }
-                }
-            }
-        }
-
-        stage('Quality Gate') {
-            steps {
-                echo "🚦 Vérification du Quality Gate SonarQube..."
-                timeout(time: 5, unit: 'MINUTES') {
-                    waitForQualityGate abortPipeline: true
-                }
-            }
-        }
-
         stage('Build Docker image') {
             steps {
                 echo "🐳 Construction de l’image Docker backend..."