Fix DNS conflict by using unique container names

- Add container_name for backend and frontend services
- Update nginx proxy to use veridian-preview-backend hostname
- Fixes issue where DNS was resolving to wrong backend container

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

docker-compose.yml

@@ -30,6 +30,7 @@ services:
       retries: 5
 
   backend:
+    container_name: veridian-preview-backend
     build:
       context: ./backend
       dockerfile: Dockerfile
@@ -93,6 +94,7 @@ services:
       - go2rtc
 
   frontend:
+    container_name: veridian-preview-frontend
     build:
       context: ./frontend
       dockerfile: Dockerfile

frontend/nginx.conf

@@ -6,7 +6,7 @@ server {
 
     # API proxy
     location /api {
-        proxy_pass http://backend:3000;
+        proxy_pass http://veridian-preview-backend:3000;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection 'upgrade';