fix: nginx config for UI serving under base path (#61)

Vite's \`base: /ui\` makes HTML reference \`/ui/assets/...\` but files are at \`/usr/share/nginx/html/assets/\` (no \`ui/\` subdir). The previous \`location /ui { try_files ... }\` couldn't find the files.

Fix: rewrite strips the base path prefix before try_files, so \`/ui/assets/foo.js\` resolves to \`/usr/share/nginx/html/assets/foo.js\`.
Reviewed-on: #61
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

ui/nginx.conf

@@ -5,7 +5,12 @@ server {
     root /usr/share/nginx/html;
     index index.html;
 
-    location ${BASE_PATH} {
+    location ${BASE_PATH}/ {
+        rewrite ^${BASE_PATH}(/.*)$ $1 break;
         try_files $uri $uri/ /index.html;
     }
+
+    location = ${BASE_PATH} {
+        return 301 ${BASE_PATH}/;
+    }
 }