caddy: serve /img/* from the homepage root

The @data path allowlist on the post-auth listener did not include /img/*,
so docs screenshots fell through to the index.html catch-all and the
browser got 200 text/html for every PNG (docs images broken live
2026-10-08). Pinned by the homepage_caddy seam.

dankclaw/Caddyfile

@@ -337,7 +337,7 @@ http://:8017 {
 			try_files /docs.html
 			file_server
 		}
-		@data path /services.json /status.json /app.js /style.css /deployed.js
+		@data path /services.json /status.json /app.js /style.css /deployed.js /img/*
 		handle @data {
 			file_server
 		}