Add ONION-URLS.md, export script, and tighten README

- ONION-URLS.md: static registry of all 43 hidden services (port, role, app path)
- scripts/export-onion-urls.sh: writes live .onion addresses to onion-urls.txt at runtime
- npm run onions:export shortcut added to package.json
- onion-urls.txt added to .gitignore (runtime artifact, not source)
- README: cohesive rewrite — architecture diagram, operator command table, source-of-truth
  map, BTCPay notes, full site map, common fixes
- BTCPay status route: awaited params destructuring (Next 15 async params)

Made-with: Cursor

package.json

@@ -12,7 +12,8 @@
     "health:stack": "bash scripts/health-check-stack.sh",
     "onions:status": "node scripts/onion-status.cjs",
     "onions:list": "bash scripts/list-onion-urls.sh",
-    "install:systemd": "bash -c 'echo Run: sudo CYBERLUX_USER=$USER bash scripts/install-systemd.sh'"
+    "install:systemd": "bash -c 'echo Run: sudo CYBERLUX_USER=$USER bash scripts/install-systemd.sh'",
+    "onions:export": "bash scripts/export-onion-urls.sh"
   },
   "dependencies": {
     "next": "16.1.7",