feat(ift): EventHub AI Router stack for Zed

FastAPI gateway with A/B/C lane orchestration, LiteLLM proxy config,
Swarm stack (postgres, redis, VPN off-by-default), deploy/smoke/audit scripts.

scripts/router-entrypoint.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+set -eu
+
+read_secret() {
+  if [ -f "$1" ]; then
+    tr -d '\n\r' < "$1"
+  fi
+}
+
+if [ -f /run/secrets/litellm_master_key ]; then
+  export LITELLM_MASTER_KEY="$(read_secret /run/secrets/litellm_master_key)"
+fi
+if [ -f /run/secrets/router_api_key ]; then
+  export ROUTER_API_KEY="$(read_secret /run/secrets/router_api_key)"
+fi
+
+exec uvicorn router:app --host 0.0.0.0 --port 8000 "$@"