Add Compose stack & Caddy deploy artifacts (task 05)

Multi-stage Dockerfile (pnpm fetch/offline, standalone output, non-root
nextjs user), deploy/compose.yaml with famapp + famapp-db + full Authentik
stack on famapp_net, Caddyfile.snippet for fam/auth.ginnoir.com, and
.env.production.example. Added .dockerignore and public/.gitkeep.

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

deploy/Caddyfile.snippet

@@ -0,0 +1,9 @@
+# Include from main Caddyfile or paste into the existing one.
+
+fam.ginnoir.com {
+    reverse_proxy famapp:3000
+}
+
+auth.ginnoir.com {
+    reverse_proxy authentik-server:9000
+}