fix(nginx): redirect unknown paths to homepage

Drop the $uri/ directory step in try_files which triggered the default
403 page on directories without an index, and 302 any 403/404 back to /.

nginx.conf

@@ -4,7 +4,7 @@ server {
     location / {
         root /usr/share/nginx/html;
         index index.html index.htm;
-        try_files $uri $uri.html $uri/index.html $uri/index.htm $uri/ =404;
+        try_files $uri $uri.html $uri/index.html $uri/index.htm =404;
     }
 
     location /.well-known/ {
@@ -13,11 +13,7 @@ server {
         add_header Access-Control-Allow-Methods "GET, OPTIONS";
     }
 
-    error_page 404 /404.html;
-    location = /404.html {
-        root /usr/share/nginx/html;
-        internal;
-    }
+    error_page 403 404 =302 /;
 
     error_page 500 502 503 504 /50x.html;
     location = /50x.html {