Add server environment example

.env.example

@@ -0,0 +1,17 @@
+# RUVNOX Tactical Server Environment
+# Copy this file to:
+# /opt/ruvnox/tactical/config/server.env
+#
+# Never commit real secrets.
+
+RUVNOX_ENV=development
+
+SERVER_HOST=0.0.0.0
+SERVER_PORT=8080
+
+# External PostgreSQL instance on CT101
+DB_HOST=192.168.178.4
+DB_PORT=5432
+DB_NAME=ruvnox_tactical
+DB_USER=ruvnox_tactical
+DB_PASSWORD=change_me