feat: nginx: cache responses from app/download.php results

This configuration change prevents the browser from systematically
downloading thumbnails of uploaded files. Because "uploads" URLs are
always pointing to the same exact file, we can cache the response.

src/nginx/common.conf

@@ -78,6 +78,18 @@ location = /nginx-status {
 # deny access to hidden files/folders
 location ~ /\.  { access_log off; log_not_found off; deny all; }
 
+# for user uploaded files, use a long cache value, as uploads are not modified anyway: an URL points always to the same exact file
+location ^~ /app/download.php {
+    more_set_headers Cache-Control "public, max-age=31536000";
+    include         /etc/nginx/fastcgi.conf;
+    fastcgi_index  index.php;
+    log_not_found off;
+
+    if (-f $request_filename) {
+        fastcgi_pass   unix:/run/php-fpm.sock;
+    }
+}
+
 # assets configuration
 location ~* \.(js|css|png|jpg|jpeg|gif|ico|map|ttf|txt|woff|woff2|svg|webmanifest)$ {
     access_log off;