Gracefully terminate tool daemons when obot exits

[njhale]

Problem

When obot server is terminated with SIGINT (kill -2 <obot-server-pid>), it's child daemon tool processes are never terminated.

This isn't great. For example, it effectively prevents developers from stopping obot server Goland/delve debug sessions without killing the daemon tool processes directly.

Solution

Ensure that obot server properly propagates termination signals (like SIGINT) to the daemon tool processes it starts before exiting.

Fix Verification Gotchas

Running Ctrl-C from a common shell -- like bash and zsh -- sends SIGINT to the entire foreground process group, which includes the tool daemons started by obot server. This bypasses the graceful shutdown logic in Obot/GPTScript and means that it can't be used to effectively verify a fix.

Instead, any fix should be verified by executing kill -2 <obot-server-pid>, which will send SIGINT to only the parent obot server process.

[njhale]

Setting this to medium because this has no immediate impact on Obot's functional features; i.e. it's pretty much only an issue during development (debugging).