docs: add AGENTS.md canonical entry point; mark FIFA23 README/CLAUDE/setup stale

AGENTS.md is the new canonical AI-agent entry point (FIFA17 active target,
repo map, FIFA23->FIFA17 pivot history). README/CLAUDE/setup.sh get stale
banners pointing to it. Retained pre-existing WIP brought forward.

setup.sh

@@ -1,5 +1,12 @@
 #!/usr/bin/env bash
-# OpenFUT Setup Script
+# OpenFUT Setup Script  —  ⚠️ LEGACY (FIFA 23 core+bridge lineage)
+#
+# SUPERSEDED. The working target is FIFA 17. This script builds/starts the old
+# FIFA 23 core+bridge stack and redirects EA domains for FIFA 23. Do NOT use it
+# for the current server. Canonical server bring-up (FIFA 17):
+#   cd fifa17-recon/docker/fifa17-python && docker compose up -d
+# Status: docs/PROJECT_STATE.md · Runbook: fifa17-recon/FUT-RUNBOOK.md
+#
 # Builds, configures, and starts the OpenFUT offline FUT emulator for FIFA 23.
 # Run as a regular user; the script will sudo only for hosts/cert/iptables steps.
 
@@ -407,6 +414,11 @@ EOF
 }
 
 # ── Dispatch ───────────────────────────────────────────────────────────────────
+# --- Legacy guard: this is the superseded FIFA 23 flow (see header banner). ---
+echo "[LEGACY] setup.sh drives the superseded FIFA 23 core+bridge stack." >&2
+echo "[LEGACY] Canonical FIFA 17 server: cd fifa17-recon/docker/fifa17-python && docker compose up -d" >&2
+echo "[LEGACY] Status: docs/PROJECT_STATE.md · Runbook: fifa17-recon/FUT-RUNBOOK.md" >&2
+
 case "${1:-help}" in
     quickstart)   cmd_quickstart ;;
     build)        cmd_build ;;