Enable storefront provision from Add Domain via optional git URL.

Persist deploy_slug on domains, call the websites agent /provision endpoint, and drop the hard-coded host map so Deploy appears from the UI.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/websites-agent/README.md

@@ -0,0 +1,8 @@
+# Websites deploy / provision agent (runs on websites VM: /opt/websites-agent)
+#
+# Endpoints (X-Deploy-Token):
+#   POST /deploy     { slug }                    — git pull + build + pm2 restart
+#   POST /provision  { slug, host, gitRepoUrl }  — clone + nginx + ecosystem + allowlist
+#   GET  /health
+#
+# Env (.env): PORT, DEPLOY_TOKEN, ALLOWED_SLUGS