Add fixed group set on ecosplay realm

- Declare the 10 application groups (gp_asso, gp_contest, gp_mail,
  gp_mailling, gp_member, gp_ndd, gp_sign, gp_ticket, super_admin_asso,
  superadmin) in the realm import JSON for fresh installs.
- Extend keycloak-init to idempotently create them via kcadm on every
  boot, so existing installs (where the realm is already imported and
  --import-realm is a no-op) also get them in sync.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

realms/ecosplay-realm.json

@@ -54,6 +54,19 @@
     "password": "BBdgb6KxRQ8mNcpWFJsZCJxbSGNdgLhKFiITMErfBlQP"
   },
 
+  "groups": [
+    { "name": "gp_asso" },
+    { "name": "gp_contest" },
+    { "name": "gp_mail" },
+    { "name": "gp_mailling" },
+    { "name": "gp_member" },
+    { "name": "gp_ndd" },
+    { "name": "gp_sign" },
+    { "name": "gp_ticket" },
+    { "name": "super_admin_asso" },
+    { "name": "superadmin" }
+  ],
+
   "clients": [
     {
       "clientId": "ecosplay-web",