WHY are these changes introduced?

E2E debug output was hard to read and didn't match what you see when running a CLI command manually:

• Commands were buried. The binary path and the full arg list were logged on a single line, so for anything with a long --path (e.g. a temp-dir app) you'd have to scroll horizontally to find the actual subcommand.

  [e2e][w0][cli] exec: node /Users/psyw/src/github.com/Shopify/cli/packages/create-app/bin/run.js --name E2E-deploy-1776837816876 --path /Users/psyw/src/github.com/Shopify/cli/.e2e-tmp/e2e-bksuZC/app-c1uMa8 --package-manager pnpm --local --template none --organization-id 161686155

• No live CLI output. With DEBUG=1, execa buffered stdout/stderr and only surfaced them after the subprocess finished. You couldn't watch CLI info boxes, success panels, or progress messages as the test ran — only a wall of text after each command completed.

WHAT is this pull request doing?

1. Two-line log format. Every exec: / spawn: entry is now split onto two lines — binary path on one, args on the next. The subcommand is the first thing you see on the args line:

   [e2e][w0][cli] exec: node /Users/psyw/src/github.com/Shopify/cli/packages/create-app/bin/run.js
   [e2e][w0][cli] app init --name E2E-deploy-1776837689829 --path /Users/psyw/src/github.com/Shopify/cli/.e2e-tmp/e2e-Hbb1z7/app-9Pbsml --package-manager pnpm --local --template none --organization-id 161686155

2. Live subprocess output under DEBUG=1. New runExeca helper pipes subprocess stdout/stderr to the parent with {end: false} (so the parent's streams aren't closed when the subprocess exits). execa still buffers internally, so captured result.stdout / result.stderr for assertions is unchanged. Applied to both exec and execCreateApp.

Net effect: running E2E tests with DEBUG=1 now streams the same info boxes, success panels, and progress messages you'd see running `shopify app deploy ...` manually, rather than a silent wait followed by a dump.

How to test your changes?

DEBUG=1 pnpm --filter e2e exec playwright test app-deploy

Expect to see:

• Each CLI invocation logged on two lines (binary → args)
• CLI info/success boxes and progress messages appearing live as the subprocess runs, not only after it exits

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows) — only affects stdout/stderr piping, platform-agnostic
• I've considered possible documentation changes — none, E2E infra only
• I've considered analytics changes to measure impact — none
• The change is user-facing — not user-facing; E2E test infrastructure only, no changeset needed