CI: make real Python lifecycle fixture deterministic on Hosted Windows #311

Parent

#258 (under #248)

Failure evidence

Exact-dev full CI run 30709378693 on commit 20ca5e4 failed in Rust tests (debug):

• test: proxy::tests::start_status_stop_real_python_proxy_on_ephemeral_port
• result: 517 passed, 1 failed, 1 ignored
• Gateway reached healthy HTTP state, then real Windows process inspection timed out while fencing the spawned PID.
• The failure is in the test fixture's PowerShell/process-inspection dependency, not in the Gateway health path.

Narrow deterministic fix

Keep the non-Windows real-system test unchanged. On Windows, use the existing controlled process-inspector test seam for the same real Python child lifecycle, while retaining the real listener/HTTP checks and graceful shutdown assertions. The fixture should prove start, status, stop, PID cleanup, and diagnostics behavior without depending on Hosted PowerShell process-inspection latency.

Do not change production process inspection, product timeouts, retries, or runtime behavior.

Acceptance criteria

• Windows fixture still starts a real bundled Python Gateway and verifies requested port, build, health, PID publication, graceful shutdown, and PID cleanup.
• Windows fixture no longer depends on real PowerShell process-inspection timing.
• Focused Rust test passes in normal and debug feature configurations.
• Exact SHA Spec/Standards review finds no P0/P1/P2.
• New PR Hosted CI / gate passes without rerunning failed jobs.
• A new exact-dev full push CI / gate passes before Beta1 promotion.

Verification-Class: strict