fix(phase3): description optional, restore nginx to host IP

- Make ledger description field optional (was required, caused 400)
- Revert nginx.conf back to 192.168.1.14:8090 (host IP, reliable)
- Keep docker-compose port mapping as 8090:8090
- Add $autoCancel:false to ledger/asset API calls

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/nginx.conf

@@ -17,7 +17,7 @@ server {
 
     # SSE realtime 连接（必须在 /api/ 之前）
     location /api/realtime {
-        proxy_pass http://gamegroup-pb:8090;
+        proxy_pass http://192.168.1.14:8090;
         proxy_http_version 1.1;
         proxy_set_header Connection '';
         proxy_set_header Host $host;
@@ -33,7 +33,7 @@ server {
     # API 代理到局域网 PocketBase
     location /api/ {
         client_max_body_size 500m;
-        proxy_pass http://gamegroup-pb:8090;
+        proxy_pass http://192.168.1.14:8090;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection 'upgrade';