Change panel port from 4000 to 20000

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -1,5 +1,5 @@
 services:
-  # Domain in Dokploy → service `panel`, port `4000`
+  # Domain in Dokploy → service `panel`, port `20000`
   panel:
     build:
       context: .
@@ -9,9 +9,9 @@ services:
       postgres:
         condition: service_healthy
     expose:
-      - "4000"
+      - "20000"
     ports:
-      - "${PANEL_PORT:-4000}:4000"
+      - "${PANEL_PORT:-20000}:20000"
     environment:
       APP_NAME: ${APP_NAME:-VpnPanel}
       SECRET_KEY: ${SECRET_KEY:-change-me-to-a-long-random-string}
@@ -48,7 +48,7 @@ services:
       - vpn_internal
       - dokploy-network
     healthcheck:
-      test: ["CMD", "curl", "-f", "http://127.0.0.1:4000/health"]
+      test: ["CMD", "curl", "-f", "http://127.0.0.1:20000/health"]
       interval: 15s
       timeout: 5s
       retries: 10