Restarting copilot uses AI credits

### Describe the bug

Since a while now using `/restart` or `/resume` (also `/update`) consumes non trivial amount of AI credits.

According to my experience there seem to be a somehow fixed amount of 174 AI credits being consumed (not sure where this number comes from). According to https://docs.github.com/de/copilot/concepts/billing/usage-based-billing-for-individuals an AI credit costs 0.01 $ resulting in an amount of 1,74 $ charged for ... nothing!

### Affected version

_No response_

### Steps to reproduce the behavior

- Do some work in copilot cli
- Use `/restart`
- Exit copilot without doing anything
- You see the session used 174 AI credits even though not a single prompt was submitted

### Expected behavior

I can restart/resume without getting charged until actually work is performed!

### Additional context

_No response_

Start by tracing the /restart, /resume, and /update command paths in the Copilot CLI and compare them with the billing or credit-usage path. Reproduce the reported session with no prompt, then verify that restarting or resuming consumes no AI credits while normal prompt usage remains accounted for.

Written by the indexing model from the issue text.