test(cli): migrate gateway-free smoke coverage

[elezar]

Summary

Move gateway-free CLI smoke coverage from the standalone Rust E2E crate into the normal openshell-cli integration-test suite. This keeps tests that need no gateway, container runtime, tmachine, or external network in the fast workspace test path.

Stack

1. test(cli): migrate gateway-free smoke coverage #3641 — gateway-free CLI smoke coverage
2. test(conformance): migrate file transfer coverage #3597 — file-transfer conformance coverage
3. test(e2e): run podman suite with tmachine #3637 — Podman E2E tmachine archive

Draft follow-up #3766 branches from #3597 for relay reconnect coverage.

Related Issue

No issue required: mechanical relocation and consolidation of existing test coverage with no user-visible behavior change.

Changes

• Added shared isolated CLI execution using CARGO_BIN_EXE_openshell with temporary user and system configuration directories
• Organized coverage into rendered help/command-shape, generic gateway registration, and Cloudflare gateway registration suites
• Consolidated two duplicate gateway-help cases while preserving all distinct assertions from the 23 original tests
• Removed e2e/rust/tests/cli_smoke.rs and e2e/rust/tests/cf_auth_smoke.rs

Testing

• mise run pre-commit passes
• Unit tests added/updated
• E2E tests added/updated (if applicable)
• cargo test -p openshell-cli --test cli_help_integration --test gateway_registration_integration --test cloudflare_gateway_integration (21 passed)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (not applicable: test-only change)

[github-actions]

Label test:e2e applied for 8d69868. Open the existing run and click Re-run all jobs to execute with the label set. The run will execute the standard E2E suite after building the required gateway, sandbox, and supervisor images once. The matching required CI gate status on this PR will flip green automatically once the run finishes.