Add port troubleshooting reference guide

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

server/PORT_TROUBLESHOOTING.txt

@@ -0,0 +1,60 @@
+================================================================================
+  COMMONWEALTH ONLINE - PORT TROUBLESHOOTING
+================================================================================
+
+ERROR: "Only one usage of each socket address ... is normally permitted"
+
+This means port 7777 is already in use by another process.
+
+QUICK FIXES:
+============
+
+Option 1: Use fix-port.bat (Recommended)
+-----------------------------------------
+1. Double-click fix-port.bat
+2. Choose an option:
+   - Press 1 to kill the blocking process and restart
+   - Press 2 to use a different port
+   - Press 3 to cancel
+
+Option 2: Manually change the port
+-----------------------------------
+1. Open commonwealth-server.json in Notepad
+2. Find the line: "port": 7777
+3. Change to a different port, e.g. "port": 8000
+4. Save the file
+5. Double-click start.bat again
+
+Option 3: Use the CLI with port override
+-----------------------------------------
+Open Command Prompt in the server folder and run:
+
+  python consumer_server_cli.py serve --config commonwealth-server.json --port 8000
+
+Option 4: Find and kill the blocking process manually
+------------------------------------------------------
+1. Open Command Prompt as Administrator
+2. Run: netstat -aon | find ":7777"
+3. Note the PID (last column)
+4. Run: taskkill /PID <PID> /F
+5. Try starting the server again
+
+CHECKING DIFFERENT PORTS:
+=========================
+
+Common available ports:
+  - 8000
+  - 8080
+  - 9000
+  - 9999
+
+Choose any port between 1024 and 65535 that isn't in use.
+
+FORWARDING FOR REMOTE CONNECTIONS:
+===================================
+
+If using a non-standard port (not 7777), remember to:
+1. Forward that port on your router
+2. Tell remote players to connect to your_ip:port_number
+
+================================================================================