fix: use full hermes path and gosu in multi-gateway launcher

- Use /opt/hermes/.venv/bin/hermes (full path) — not on PATH
  before entrypoint.sh sources the venv
- Wrap with gosu hermes to avoid root guard in gateway run
- Add error check if hermes binary doesn't exist

run-multi-gateways.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+# Multi-gateway launcher for HERMES_PROFILES env var.
+# Reads comma-separated profile names, spawns one gateway per profile.
+# Designed to run before the main entrypoint — gateways run in background.
+set -e
+
+if [ -z "${HERMES_PROFILES}" ]; then
+  echo "HERMES_PROFILES not set — skipping multi-gateway launch"
+  exit 0
+fi
+
+# Source venv to make 'hermes' available (entrypoint.sh sources it later,
+# but we need it NOW for the background gateways)
+HERMES_BIN="/opt/hermes/.venv/bin/hermes"
+if [ ! -x "$HERMES_BIN" ]; then
+  echo "ERROR: hermes binary not found at $HERMES_BIN"
+  exit 1
+fi
+
+mkdir -p /opt/data/logs
+
+IFS=',' read -ra PROFILES <<< "${HERMES_PROFILES}"
+for profile in "${PROFILES[@]}"; do
+  profile="$(echo "${profile}" | xargs)"  # trim whitespace
+  [ -z "${profile}" ] && continue
+
+  echo "Starting gateway for profile: ${profile}"
+  API_SERVER_ENABLED=false \
+    nohup gosu hermes "$HERMES_BIN" --profile "${profile}" gateway run \
+      >> "/opt/data/logs/gateway-${profile}.log" 2>&1 &
+done
+
+echo "All gateways launched: ${HERMES_PROFILES}"