fix(translate): handle row lock timeout in cancel, add flush fallback, migrate progress to store

- Extract _fallback_cancel_request for row lock timeout recovery in orchestrator_cancel
- Add flush lock timeout fallback in cancel_run
- Set error_message when all records fail in executor
- Track insert_failed state in scheduler and frontend store
- Migrate TranslationRunProgress from local polling to centralized store
- Fix nginx resolver for Docker variable-based proxy_pass
- Add FRONTEND_HOST_PORT env var to docker-compose

docker/nginx.conf

@@ -1,6 +1,7 @@
 server {
     listen 80;
     server_name _;
+    resolver 127.0.0.11 ipv6=off;
 
     root /usr/share/nginx/html;
     index index.html;
@@ -10,7 +11,8 @@ server {
     }
 
     location /api/ {
-        proxy_pass http://backend:8000/api/;
+        set $backend_api http://backend:8000;
+        proxy_pass $backend_api;
         proxy_http_version 1.1;
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
@@ -20,7 +22,8 @@ server {
     }
 
     location /ws/ {
-        proxy_pass http://backend:8000/ws/;
+        set $backend_ws http://backend:8000;
+        proxy_pass $backend_ws;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection "upgrade";