Corrige la redirection login derrière un reverse proxy (AUTH_URL)

La redirection vers /login utilisait http://localhost:8413 (ancienne valeur par
défaut d'AUTH_URL). On retire ce défaut localhost : AUTH_URL prend la valeur
fournie (ex. https://pleinr.ffnancy.fr) et pilote la redirection. Ajout de
AUTH_TRUST_HOST=true (confiance aux en-têtes X-Forwarded-*) et l'entrypoint
supprime AUTH_URL si vide. Vérifié : la redirection pointe vers le domaine public.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XwfhYHzC9hQWPDnQ2p53GL

docker-compose.yml

@@ -41,7 +41,12 @@ services:
       # Optional: if left empty, the container generates and persists one
       # automatically (see docker-entrypoint.sh + the app-data volume).
       AUTH_SECRET: ${AUTH_SECRET:-}
-      AUTH_URL: ${AUTH_URL:-http://localhost:8413}
+      # IMPORTANT behind a reverse proxy: set AUTH_URL to your public URL so the
+      # login redirect points to the right host, e.g.
+      #   AUTH_URL=https://pleinr.ffnancy.fr
+      AUTH_URL: ${AUTH_URL:-}
+      # Lets Auth.js trust the X-Forwarded-* headers from the proxy.
+      AUTH_TRUST_HOST: "true"
       SEED_ON_START: ${SEED_ON_START:-true}
       SEED_ADMIN_EMAIL: ${SEED_ADMIN_EMAIL:-admin@plein-r.fr}
       SEED_ADMIN_PASSWORD: ${SEED_ADMIN_PASSWORD:-changeme123}