feat: module viewServices — gestion services systemd via systemctl

- module.json : métadonnées du module (nav_href, nav_icon, nav_color, nav_label_key)
- backend/go.mod : dépendance sur core/backend via replace directive
- backend/services.go : implémente modules.Module, routes /api/services et /api/services/{name}/*
  - Utilise r.RunOnTarget du Registry (pas d'accès internal)
  - Liste services, statut détaillé, actions start/stop/restart/reload/enable/disable
  - Enregistrement du nav item via r.RegisterNavItem
- frontend/services.html : page de gestion des services systemd
  - Composant servicePage Alpine.js inline (autonome, indépendant de core app.js)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

module.json

@@ -0,0 +1,12 @@
+{
+  "id": "viewServices",
+  "name": "Services",
+  "description": "Gestion des services systemd via systemctl",
+  "version": "1.0.0",
+  "author": "proxmoxPanel",
+  "core_min_version": "1.0.0",
+  "nav_href": "/viewServices/services.html",
+  "nav_icon": "lnid-gear-2",
+  "nav_color": "#fb923c",
+  "nav_label_key": "nav.services"
+}