feat: render gotestout activity as transient block

[evanmschultz]

Summary

• replace gotestout's one-line transient activity footer with a wrapped multi-line activity block
• keep the spinner/header at the top and move package, test, counts, and elapsed data onto separate lines
• refresh docs, goldens, and VHS assets so the shipped examples match the new live activity behavior

Validation

• go test ./...
• go test ./internal/examples -args -update
• go test ./examples/all -args -update
• go test ./examples/gotestout -args -update
• go test ./gotestout -run 'TestRenderPlainCompactGolden|TestRenderHumanStyledCompactGolden' -args -update
• mage vhs

Release

• latest tag is v0.2.2
• recommend next release tag v0.2.3 after this lands on green main
• dependents should only need: go get github.com/evanmschultz/laslig@v0.2.3 && go mod tidy