Scaffold weather app: reception forecast display + shared internal API

- Backend: Fastify service polling Met Office DataHub (Global Spot: hourly,
  three-hourly, daily endpoints) with Open-Meteo fallback, hourly refresh.
  Reuses settings' hotel_location/met_office integrations (same pattern as
  hvac's lib/weather.js) rather than its own credential copy.
- Three display tiers stored in one forecast_points table: today (hourly),
  next 2 days (3-hourly), days 4-7 (plain daily) - 7 days total.
- Public /api/public/forecast (no auth) feeds the reception kiosk display;
  /api/internal/forecast (WEATHER_SECRET bearer) lets other apps read the
  stored forecast instead of polling providers themselves; /api/admin/*
  (normal JWT + settings cap) is the staff status/refresh page.
- Frontend: root / is the public full-screen Display (no AuthGate at all -
  first genuinely public app in the stack); /admin is the authed status
  page. apps.base_path is /weather/admin so the portal card opens the
  admin view directly, precedented by forecasting's history sub-route.
- LXC 131 / 10.10.10.131, registered in auth/src/db.js, push-to-forgejo.sh,
  and stack-init/install-stack.sh (deploy_weather + --only dispatch + full
  install chain).
- Typechecks and builds clean; not yet deployed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "hnf-weather-backend",
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "start": "node src/index.js",
+    "dev": "node --watch src/index.js"
+  },
+  "dependencies": {
+    "@fastify/cookie": "^9.4.0",
+    "@fastify/cors": "^9.0.1",
+    "fastify": "^4.28.1",
+    "jose": "^5.9.6",
+    "pg": "^8.13.1"
+  }
+}