fix(lightsail): derive Remote Control name from the public host

[defangdevs]

Problem

aws/lightsail-template.yaml hardcoded the Remote Control session name:

remoteControlName = "${UserName}@${StackName}";

Two issues with that:

1. The name shown in the Claude apps was the CloudFormation stack name, which says nothing about how to reach the box.
2. remoteControlName is a per-user option, so it pinned one name across every session that user runs. Sessions added at runtime all collided on the same label.

The EC2 template already does the right thing (aws/template.yaml:634), so this was Lightsail-only drift.

Fix

Drop the hardcoded name and set remoteControlHost = hostname at the services.agent-box level, mirroring EC2. The module then derives <user>-<session>@<host> per session, where <host> is the sslip.io address the box is actually reached at.

Before → after, for stack my-box at 1.2.3.4:

	name in Claude apps
before	agent@my-box
after	agent-main@1-2-3-4.sslip.io

Three coupled edits fall out of it:

• RemoteControlSession Output advertised the old shape, so it moves in lockstep. It uses the same dashed-IP form the userdata bakes into hostname (tr . -) and that WebUrl already reports — verified the two agree.
• Fn::Sub StackName variable is now unreferenced in the userdata, so it is removed.
• UserName parameter description mentioned the old <user>@<stack> shape.

Also here

README.md:43 documented <UserName>@<stack name> for the EC2 walkthrough. That has been stale since aws/template.yaml started setting remoteControlHost — it is corrected in the same pass since it is the identical claim.

Verification

• yamllint parses the template clean (with key-duplicates enabled).
• hostname is in scope where remoteControlHost now reads it — same let block, aws/lightsail-template.yaml:368.
• Grepped for any remaining ${StackName} reference inside the Fn::Sub: none.

Not deploy-tested — I have no Lightsail stack to launch, and the change is in userdata that only runs on first boot. Worth a real launch before merge if you want the Output confirmed end-to-end.

🤖 Generated with Claude Code

https://claude.ai/code/session_01PsqGhkpjsb4kKAdVz25xKN