/previz: remove password protection

Pages stay unlisted (noindex, not in sitemap, not linked) and uncached.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker/nginx.conf

@@ -23,12 +23,9 @@ server {
         add_header Cache-Control "public, max-age=604800";
     }
 
-    # Client previz pages: password protected (file lives on the server, see DEPLOY.md).
-    # ^~ beats the media regex above, so nothing in here gets a public cache header
-    # and Cloudflare never serves it to someone who hasn't logged in.
+    # Client previz pages: never cached, so updated renders show up straight away.
+    # ^~ beats the media regex above, so nothing in here gets the week-long cache.
     location ^~ /previz/ {
-        auth_basic "Two Tales VFX previz";
-        auth_basic_user_file /etc/nginx/auth/previz.htpasswd;
         add_header Cache-Control "private, no-store";
         try_files $uri $uri/ $uri.html =404;
     }