Support a remote ComfyUI via a .env config file

- run.sh / run.ps1: load an optional .env for host-specific env vars
- .env.example + docs: ComfyUI can run on another host (ROUTER_COMFYUI)
- .gitignore: .env

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

run.sh

@@ -5,6 +5,9 @@ set -uo pipefail
 cd "$(dirname "$0")"
 export PATH="/opt/homebrew/bin:/usr/bin:/bin:/usr/sbin:/sbin:${PATH:-}"
 
+# optional local config (host-specific env vars, kept out of git — see .env.example)
+[ -f .env ] && { set -a; . ./.env; set +a; }
+
 # clear any stale instances via recorded PIDs (never pattern-match — that can
 # match unrelated processes, including a shell that merely mentions "router.py")
 for pf in .litellm.pid .router.pid; do