feat: improve collaboration rooms (#1338)

docker/docker-compose.yml

@@ -15,6 +15,11 @@ services:
       # Where guacd stores files for RDP drive redirection (one folder per
       # user is created underneath). Must be writable by guacd's user.
       GUACD_DRIVE_PATH: "/termix-data/rdp-drive"
+      # Multi-instance deployments should point every backend at the same
+      # Redis. Without it, collaboration rooms keep their single-instance
+      # in-memory fallback.
+      # REDIS_URL: "redis://redis:6379"
+      # TERMIX_REDIS_PREFIX: "termix:collab"
       # Hardened deployments can require keys from environment variables or
       # Docker secrets mounted through JWT_SECRET_FILE, DATABASE_KEY_FILE,
       # ENCRYPTION_KEY_FILE and INTERNAL_AUTH_TOKEN_FILE.