Homepage: give the user page its own login (dankuser)

The homepage user page + shared data now use a dedicated CADDY_HOMEPAGE_HASH
(username dankuser), separate from the shared family password (CADDY_BASICAUTH_HASH,
username dank, still used by the other vhosts) and the operator password
(CADDY_ADMIN_HASH, username frank, the /admin/ page). This lets the homepage be
re-logged independently without touching the other sites. deploy.sh renders the
new placeholder; the .env.example documents all three hashes.

dankclaw/Caddyfile

@@ -67,16 +67,16 @@ dankclaw.franksdank.cloud {
 	@data path /services.json /status.json /app.js /style.css /deployed.js
 	handle @data {
 		basicauth {
-			dank REPLACE_WITH_HASH
+			dankuser REPLACE_WITH_HOMEPAGE_HASH
 			frank REPLACE_WITH_ADMIN_HASH
 		}
 		file_server
 	}
 
-	# Everything else (the user page): the family (Q18).
+	# Everything else (the user page): the homepage login (dankuser).
 	handle {
 		basicauth {
-			dank REPLACE_WITH_HASH
+			dankuser REPLACE_WITH_HOMEPAGE_HASH
 		}
 		try_files /index.html
 		file_server