Pages show the hall-wide notice, when there is one, at the top

The keeper's hall-announce writes one file on the shared host; the site
serves it at /hall/announcement.json, and the banner shows it with the time
in the reader's own clock, dismissable one notice at a time.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jm2auWk6RP71CjaAb4FMoG

deploy/Caddyfile.tmpl

@@ -1,6 +1,13 @@
 # Wiz-War's site on a host shared with the other games of Kestrel's Hall:
 # setup-droplet.sh fills __HOST__ and writes it to /etc/caddy/sites/wizwar.caddy.
 __HOST__ {
+	# The hall-wide notice (hall-announce on the host): one file, served by every game's site.
+	handle_path /hall/* {
+		root * /var/lib/hall
+		header Cache-Control "no-store"
+		file_server
+	}
+
 	header {
 		Strict-Transport-Security "max-age=31536000"
 		X-Content-Type-Options "nosniff"