feat: update nginx.conf for deployment

conf/nginx.conf

@@ -15,6 +15,12 @@ http {
                       '$status $body_bytes_sent "$http_referer" '
                       '"$http_user_agent" "$http_x_forwarded_for"';
 
+    # Browser preferred language detection (does NOT require AcceptLanguageModule)
+    map $http_accept_language $accept_language {
+        ~*^zh zh;
+        ~*^en en;
+    }
+
     access_log  off;
     log_not_found  off;
     sendfile        on;
@@ -28,6 +34,19 @@ http {
         location / {
             root   /usr/share/nginx/html;
 
+            # Fallback to default language if no preference defined by browser
+            if ($accept_language ~ "^$") {
+                set $accept_language "fr";
+            }
+            # Redirect "/" to Angular application in the preferred language of the browser
+            rewrite ^/$ /$accept_language permanent;
+
+            # Everything under the Angular application is always redirected to Angular in the
+            # correct language
+            location ~ ^/(zh|en) {
+                try_files $uri /$1/index.html?$args;
+            }
+
             index  index.html;
             try_files $uri $uri/ /index.html;