feat: support jump host ports in SSH menu

Allow jump host definitions to include an explicit port in the form user@host:port.
Default to port 22 when no port is provided and update the sample config and docs accordingly.

README.md

@@ -45,6 +45,8 @@ ssh:
   default_options: ""
   jump_hosts:
     office: "user@192.168.10.11"
+    office-alt: "user@192.168.10.11:2222"
+
 ```
 
 ### `hosts/dev.yaml`
@@ -98,6 +100,7 @@ A complete sample configuration is available in `sample-config/`.
 ## Notes
 
 - `jump_host` values are resolved by name from `global.yaml`.
+- Jump hosts support `user@host` and `user@host:port`; if the port is omitted, `22` is used.
 - If a host does not define a user or port, global defaults are used.
 - `default_options` is present in the config but not consumed by the current script.
 - The sample config includes `ssh_options` in one file, but the current script does not consume it yet.