Add `LIGHTNING_WS_HOST` to separate Commando host from Core Lightning's host

[ShahanaFarooqui]

Currently, Commando can only run on the same IP as Core Lightning. As a result, we have been using the same LIGHTNING_HOST variable for connecting both to CLN and Commando.

However, this approach creates a problem when the Core Lightning container runs inside Docker. The LIGHTNING_HOST now points to Docker’s internal IP, which is not reachable externally for Commando's connection URI.

Proposed Solution:

• Introduce a new environment variable named LIGHTNING_WS_HOST.
• Use LIGHTNING_WS_HOST specifically for Commando’s WebSocket connection URI.
• Retain LIGHTNING_HOST for internal Core Lightning connections.
• Ensure Commando connection logic gracefully handles cases if one of the variables is mis-configured.