fix(integration-tests): use spawnSync to capture stdout+stderr (CI fix)

[bakeb7j0]

Summary

Follow-up to PR #410. The execSync(cmd 2>&1) approach didn't work in GitHub Actions runners — gh --help still produced empty output even with stderr merged. Switching to spawnSync which gives separate stdout/stderr buffers we can concatenate.

Also unsets pager environment variables (GH_PAGER, PAGER, GLAB_PAGER) to defeat any pager-detection short-circuiting — some gh versions check terminal capabilities and suppress --help output if pagination is unavailable.

Changes

• tests/integration/cli-flag-shapes.test.ts:
  • captureHelp() now uses spawnSync instead of execSync
  • Concatenates result.stdout + result.stderr
  • Unsets pager env vars

Tests

• ✅ 18/18 pass locally
• Goal: unblock the kahuna→main merge (PR plan(#390): Bug Drain + Feature Adds — kahuna to main (10 issues) #402) which is failing on these tests in CI

Why this matters

PR #410's first attempt didn't work because shell-level 2>&1 doesn't capture output that gh writes via TTY-aware paths. spawnSync bypasses the shell entirely and captures the actual file descriptors.