Change le mapping des ports hôte vers des ports peu courants

- App : 8413 (hôte) → 3000 (conteneur)
- Postgres : 54329 (hôte) → 5432 (conteneur)
AUTH_URL, .env.example et README mis à jour en conséquence. Les ports internes
des conteneurs (3000, 5432) et DATABASE_URL (réseau interne) restent inchangés.

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

.env.example

@@ -1,6 +1,8 @@
 # ---- Database (external Postgres) ----
-# When running the app via docker-compose, host is the compose service name "postgres".
-# For local dev outside Docker, use localhost.
+# When running the app via docker-compose, host is the compose service name
+# "postgres" on the internal port 5432 (NOT the published host port).
+# For local dev outside Docker against the dockerised Postgres, use
+# localhost on the published host port: postgres://pleinr:pleinr@localhost:54329/pleinr
 DATABASE_URL=postgres://pleinr:pleinr@postgres:5432/pleinr
 
 # Individual vars consumed by the postgres container in docker-compose.yml
@@ -11,8 +13,9 @@ POSTGRES_DB=pleinr
 # ---- Auth.js (NextAuth v5) ----
 # Generate with: openssl rand -base64 32
 AUTH_SECRET=change-me-to-a-long-random-string
-# Public URL of the app (used by Auth.js for callbacks)
-AUTH_URL=http://localhost:3000
+# Public URL of the app (used by Auth.js for callbacks).
+# With docker-compose the app is published on host port 8413 by default.
+AUTH_URL=http://localhost:8413
 
 # ---- First admin user (created by the seed script) ----
 SEED_ADMIN_EMAIL=admin@plein-r.fr