Add terminal-driven E2E coverage for v3 CLI recovery and readiness

[hatayama]

Background

v3 now relies on the native CLI, project-local IPC, and readiness/recovery state files. Unit tests and focused Unity tests cover the state model, but we still need a repeatable end-to-end test that runs from outside Unity like a real user command.

This should follow the v3 direction: terminal-driven E2E, not long-running Unity EditMode tests that block the editor thread.

Goal

• Verify that CLI commands recover reliably after Unity startup, compile/domain reload, and server recovery.
• Verify that the CLI does not wait forever when readiness state is stale or failed.
• Keep the test usable locally and in CI-like environments without depending on ambient editor scene state.

Candidate Tasks

• Add a POSIX-friendly E2E harness under scripts/ that runs real uloop commands against a target Unity project with --project-path.
• Cover at least: readiness check, compile --wait-for-domain-reload, immediate get-logs, and execute-dynamic-code after recovery.
• Add stale recovery-state coverage that proves the CLI exits with actionable guidance instead of waiting until timeout.
• Decide whether to extend scripts/smoke-compile-get-logs.py, add a new recovery-specific script, or integrate into the existing terminal-driven E2E helpers.
• Document how to run the E2E locally, including any Unity/Test Framework/Input System prerequisites.

Acceptance Criteria

• The E2E launches or reuses the intended Unity project and never starts duplicate Unity instances for the same project.
• Every uloop invocation passes an explicit --project-path.
• The test owns required scene/setup preconditions instead of relying on the currently open scene.
• The test has bounded timeouts and prints enough stdout/stderr/state context to diagnose failures.
• The test avoids Unity EditMode patterns known to freeze the editor: no main-thread blocking waits, no long-lived background tasks inside Unity tests, and no nested test runner orchestration.
• The final command sequence passes on the v3 branch with the checked-in native CLI binary.

Related Context

• PR fix: CLI commands recover reliably after Unity reloads #1136 adds state-file readiness and recovery handling for domain reload/startup/compile flows.
• Existing helpers include scripts/smoke-compile-get-logs.py, scripts/smoke-uloop-launch.py, and scripts/run-windows-e2e.ps1.
• v2 had integrated CLI E2E coverage; v3 should keep the spirit but prefer terminal-driven coverage around the native CLI contract.