Better logging with sums of token usage

[rxdt]

Currently, agent logs are written to the repo + streamed.

1. It would be simple to parse the logs and create a summary of

• input/cache/output tokens used
• Other interesting details of note

2. Requires a new logging module

• Claude output varies by session
• Codex logs are consistent + also duplicated in ~/.codex (but we respectfully don't want to mess with files outside a repo)
• agy and Copilot logs need to be inspected for shape
• harness status is already wired as a command to get the link to the latest log
• Account for installed jq, or other tool usage, for pretty print + Rich/Typer is already in the harness

[rxdt]

Decide: use local scratchpad runs or re-use agent logs

e.g. ~/.codex/sessions/2026/06/27/rollout-2026-06-27T21-32-50-019f0c80-6d00-70a2-85c6-2abd0b92a3ff.jsonl
~/.claude/projects/<encoded-project-path>/<session-id>.jsonl
> find . -name '*.jsonl' -newermt "$(date +%F) 00:00:00"

or use the /scratchpad the repo has for agents to sandbox in (so they do not have to write outside repo for anything)