fix(metrics): send metrics=all for summary and aggregate

[doodaaatimmy-creator]

Summary

• add metrics=all by default for metrics summary
• add metrics=all by default for metrics aggregate
• keep the existing v2=true aggregate query intact
• add focused client regression tests for both request shapes

Repro

eightctl metrics summary -v
eightctl metrics aggregate -v

Before this change, both endpoints could fail with:

{
  "errors": {
    "metrics": ["The metrics field is required."]
  }
}

Testing

go test ./internal/client

Closes #18