test: one CLI runner for the tests that execute the built bundle (code, stdout, stderr, diagnostics on failure) #1100

Two doctor tests, two CLI runners. tests/e2e/doctor-smoke.test.ts has its own runCli that resolves { code, stdout, stderr } and rejects only on a spawn failure or a timeout; tests/integration/cli/doctor-codelldb-version.test.ts runs the bundle through promisify(execFile) and, since #1099, rethrows a failure with the exit code, signal, killed flag, stdout and stderr attached. Both shapes are right; having both is the odd part, and the other bare promisify(execFile) test sites would lose their output the same way #1098 did:

• tests/integration/cli/package-contents.test.ts (tar -czf)
• tests/e2e/docker/docker-smoke-cobol-attach.test.ts (docker exec)
• tests/e2e/npx/npx-test-utils.ts (tar -tzf)

Proposal, small: one runCli(command, args, options) in tests/test-utils/helpers/cli-bundle.ts (beside requireCliBundle) returning { code, signal, stdout, stderr }, rejecting only on a spawn failure or a kill with #1099's diagnostic shape (exit code, signal, killed, stdout, stderr, cause), windowsHide: true and a maxBuffer suited to a JSON report. The two doctor tests adopt it; the tar/docker sites can follow when touched. No behaviour change in the tests' assertions — this is about what a failure prints.

Not urgent: nothing fails today. Filed from the #1099 review so the pattern lands in one place instead of five.