feat(nginx-strangler): route /api/v1/admin/roles to server-nestjs

server-nestjs already excludes OIDC-backed role ids from member counts,
while the frozen legacy handler computes NaN for them, fails the response
contract and turns GET /api/v1/admin/roles/member-counts into a 500.

The route flip depends on the adminRole event bridge (#2749) landing
first.

Refs #2781

Co-authored-by: Automata <automata@shikanime.studio>
Signed-off-by: William Phetsinorath <william.phetsinorath-open@interieur.gouv.fr>
Change-Id: I7d36cd930692f7b476d37909077bb7166a6a6964

Author: shikanime

apps/nginx-strangler/conf.d/routing.conf

@@ -61,6 +61,15 @@ server {
     }
 
     # ── Routes migrées vers NestJS ────────────────────────────────────────────────
+    location /api/v1/admin/roles {
+        proxy_pass         http://server-nestjs;
+        proxy_http_version 1.1;
+        proxy_set_header   Host              $host;
+        proxy_set_header   X-Real-IP         $remote_addr;
+        proxy_set_header   X-Forwarded-For   $proxy_add_x_forwarded_for;
+        proxy_set_header   X-Forwarded-Proto $scheme;
+    }
+
     location /api/v1/users {
         proxy_pass         http://server-nestjs;
         proxy_http_version 1.1;