[Docs] Update VP proxy docs, ports, and diagram for #757

- Add ports 6000 (file transfer) and 322 (RTSP camera) to Dockerfile
    EXPOSE and docker-compose.yml bridge mode port mapping
  - Update migration doc with new proxy mode port requirements
  - Regenerate proxy-mode-diagram.png with all proxied ports

docs/migration-vp-ftp-port.md

@@ -1,11 +1,11 @@
-# Migration: Virtual Printer FTP Port Change (9990 -> 990)
+# Migration: Virtual Printer Port Changes
 
-## What Changed
+## FTP Port Change (9990 → 990)
 
 The Virtual Printer FTP server now binds **directly to port 990** instead of port 9990.
 Previously, an iptables `REDIRECT` rule was required to forward port 990 to 9990.
 
-## Why
+### Why
 
 The iptables `REDIRECT` target rewrites the destination IP to the **primary address
 of the incoming network interface**. When running multiple virtual printers on
@@ -16,6 +16,18 @@ when VPs have different access codes.
 By binding directly to port 990, iptables is no longer involved and each VP's
 FTP server correctly receives only its own traffic.
 
+## New Proxy Mode Ports (6000, 322)
+
+Proxy mode now requires two additional ports:
+
+| Port | Protocol | Purpose |
+|------|----------|---------|
+| 6000 | TCP/TLS | File transfer tunnel (verify_job + print uploads) |
+| 322 | TCP/TLS | RTSP camera streaming (X1/H2/P2 series) |
+
+These ports are proxied automatically — no iptables rules needed. If you have
+a firewall, ensure these ports are open between the slicer and Bambuddy.
+
 ## Migration Steps
 
 ### Linux (Native / systemd)