Standardize SurClaw ports away from defaults

- Change the API default listen port from 3000 to 3100 and include the Docker frontend origin in default CORS.

- Point Vite's default API proxy, Docker API container port, and Nginx upstream to 3100.

- Keep Docker host ports on 4002 for web, 3002 for API, and 5433 for PostgreSQL.

- Update environment examples and documentation to remove stale localhost:3000 guidance.

nginx.conf

@@ -17,7 +17,7 @@ server {
     }
 
     location /api/ {
-        proxy_pass http://api:3000/api/;
+        proxy_pass http://api:3100/api/;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection $connection_upgrade;