fix(deploy): serve under /xll-bi/ prefix and bump host port to 8214

Reverse proxy at demo-ctx.lnh2e.com forwards /xll-bi/* unchanged to the
container, so the container's nginx must match that location and Vite
must build asset URLs under the same prefix — otherwise the SPA shell
returns 404 and the JS/CSS resolve to /assets/* with no handler.

- nginx.conf: rename location /bi/ → /xll-bi/ (and assets sub-location)
- vite.config.ts: set base: '/xll-bi/' so built index.html references
  /xll-bi/assets/*
- docker-compose.yml: 8114 → 8214 to match the upstream the proxy targets

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nginx.conf

@@ -4,12 +4,12 @@ server {
     root /usr/share/nginx/html;
     index index.html;
 
-    location /bi/ {
+    location /xll-bi/ {
         alias /usr/share/nginx/html/;
-        try_files $uri $uri/ /bi/index.html;
+        try_files $uri $uri/ /xll-bi/index.html;
     }
 
-    location /bi/assets/ {
+    location /xll-bi/assets/ {
         alias /usr/share/nginx/html/assets/;
         expires 1y;
         add_header Cache-Control "public, immutable";