feat: update `gc session logs <session-id>` to show the fully enriched content

[csells]

Before you continue

• I searched existing issues and did not find a duplicate.
• I can explain the user problem this solves, not just the implementation I prefer.

Problem to solve

The following shows the tool calls that do the actual work, but the actual work part isn't show:

Proposed change

I'd like to be able to see the details of the actual work.

also I'd like an --output-format json so that I can process the output programmatically as well.

Alternatives considered

No response

Scope and impact

No response