Production-ready wiring: VAPID prop fix, port mappings, AUTH_URL

- PushOptIn now accepts vapidKey as a prop from its server-component
  parent (settings page reads VAPID_PUBLIC_KEY at runtime) — eliminates
  the NEXT_PUBLIC_* build-time dependency so pre-built GHCR images work
  without a build arg.
- deploy/compose.yaml: famapp exposes 3010:3000, authentik-server exposes
  9200:9000 so the existing Caddy stack can proxy by IP, matching every
  other service in the homelab.  NEXT_PUBLIC_APP_URL replaced by AUTH_URL
  (correct next-auth v5 var).
- deploy/Caddyfile.snippet: updated to 192.168.1.69:3010 / :9200.
- .env.production.example: AUTH_URL, ntfy pre-wired to ntfy.ginnoir.com,
  VAPID_SUBJECT prefilled with real email.
- typecheck and pnpm build both pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deploy/Caddyfile.snippet

@@ -1,9 +1,10 @@
-# Include from main Caddyfile or paste into the existing one.
+# famapp — paste into your existing Caddyfile.
+# famapp runs on 3010, authentik-server on 9200 (both bound to the host by deploy/compose.yaml).
 
 fam.ginnoir.com {
-    reverse_proxy famapp:3000
+    reverse_proxy 192.168.1.69:3010
 }
 
 auth.ginnoir.com {
-    reverse_proxy authentik-server:9000
+    reverse_proxy 192.168.1.69:9200
 }