Require integration tests in the PR template and read-only smoke tests #2685

Task summary

Part of #2682

1. PR template gate
   Add a checklist item to .github/PULL_REQUEST_TEMPLATE.md requiring a relevant integration test (in cli/src/test/integration-tests/) for commandlet changes, mirroring the "Testing instructions" section.

2. Read-only smoke tests
   Add one integration test per command in cli/src/test/integration-tests/ or the safe, no-download, no-network, all-OS commands:

   • version.sh -> ide version; assertThat contains the version
   • status.sh -> ide status; assertThat contains "Status"
   • env.sh -> ide env; assertThat contains "PATH"
   • complete.sh -> ide complete; assert non-empty / exit 0

Additional context

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