Refactor Dockerfile and Helm chart to enhance security and user permissions

- Updated Dockerfile to run as non-root user 'nginx' and adjusted Nginx configuration for improved security.
- Added pod security context in values.yaml to align with the non-root user setup.
- Refined deployment.yaml to utilize the new pod security context for better compliance with Kubernetes security standards.

talks-slides-dist/values.yaml

@@ -17,6 +17,14 @@ slides:
   # Port d’écoute dans le conteneur (doit correspondre à server/nginx/default.conf, ex. 8080).
   containerPort: 8080
 
+  # Aligné sur l’utilisateur nginx de l’image (UID/GID 101). L’image utilise USER nginx.
+  podSecurityContext:
+    runAsUser: 101
+    runAsGroup: 101
+    runAsNonRoot: true
+    seccompProfile:
+      type: RuntimeDefault
+
   service:
     type: ClusterIP
     # Port du Service (Ingress pointe ici) ; le trafic est envoyé vers containerPort sur les pods.