Add run meta stats to artifacts

[tusharshah21]

Summary

Added run-level statistics capture and persistence so each run writes a meta.json under its run directory, then exposed that metadata through the artifacts command output.

This was done to satisfy the issue requirement to track and retrieve:

• LLM credits used
• POVs found
• Seeds shared
• Number of builds requested through libCRS

User Impact

• User-facing change
• Internal-only change

CLI/API/config/docs impact and migration:

• CLI output change: artifacts JSON now includes a top-level meta object when resolving a run.
• No new required flags and no command rename/removal.
• Existing consumers that ignore unknown JSON fields continue to work.
• Consumers with strict JSON schema validation should allow the new optional meta field.

Release Note / Changelog

• I updated CHANGELOG.md ([Unreleased]) for user-facing changes
• No changelog entry needed (internal-only refactor/test/chore)

Deprecation or breaking behavior:

• None.
• No replacement path needed.
• No planned removal window.

Validation

• Added/updated unit test coverage for artifacts meta output behavior.
• Ran static diagnostics on changed files with no reported errors.
• Attempted targeted pytest run for the updated artifacts test module, but local execution in this Windows environment is blocked during collection by a Linux-only fcntl import dependency.

Checklist

• I followed Conventional Commits
• I updated docs for behavior/config/CLI changes
• I added/updated tests for behavior changes
• I considered backward compatibility and migration impact

Closes #80

[azchin]

Thanks, could change the meta.json format to something like the snippet below? There's additional implementation change requests commented.

Also please sign your commits and use Conventional Commits for commit messages.

{
  "totals": {
    "artifacts": {
      "povs": 2,
      "seeds": 4,
      "patches": 1,
      "bug_candidates": 2
    },
    "llm": {
      "credits_used": 1.65
    },
    "sidecar": {
      "patch_builds": 4,
      "patch_tests": 2,
      "pov_runs": 8
    }
  },
  "crs": {
    "crs_a": {
      "artifacts": {
        "povs": 2,
        "seeds": 3,
        "patches": 1,
        "bug_candidates": 0
      },
      "llm": {
        "credits_used": 1.25
      },
      "sidecar": {
        "patch_builds": 4,
        "patch_tests": 2,
        "pov_runs": 7
      }
    }
  }
}

[azchin]

I also don't like the scrape of the logs for counting build requests. Please modify libCRS itself to log more systematically to a file, similar to my feedback for counting LiteLLM requests.

Also, please count the number of requests for run-pov and apply-patch-test as well. And do it per-CRS.

[tusharshah21]

noted

[tusharshah21]

schema update to nested totals + per-CRS (patches, bug_candidates), structured JSONL metrics replacing log scraping, LiteLLM spend polling via /global/spend/report, and artifact counting centralized in WorkDir are all clean and cohesive enough to ship as one PR. CI green, no split needed.
Let me know if there are any other suggestion!