[RomainROCH]

What this PR does

Synchronizes the status worker's final shutdown check and pipe-instance creation with the shutdown request. The mutex is released before ConnectNamedPipe; shutdown sets its flag under the same mutex and wakes afterward. Failed-startup cleanup also wakes status when its ready ACK is still queued.

Adds a process-isolated regression that observes actual mutex contention, verifies worker/UI joins and endpoint cleanup, and preserves failure after any rescue connection. Test hooks compile only under cfg(test).

Base: main at 1b95562. Local head: f639b56. Two files changed. PR10 remains a separate draft diagnostic.

Why

Shutdown could attempt its only wake while no status instance existed, then join a worker that created its next pipe and waited indefinitely for a client. The exact final regression fails on the old main worker with ERROR_FILE_NOT_FOUND, requires an owned-fixture rescue, verifies cleanup and returns exit101. The corrected worker finishes without rescue. This reproduces a real defect; the historical CI stall's cause remains unproven.

How it was tested

• Same final fixture on old and corrected workers, unique inert endpoints and no protection runtime.

• Safe Rust aggregate: 85 successful executions including one nested child; native Power Request acquisition test explicitly skipped.

• Formatting check, strict Clippy all-targets/all-features and release MSVC build: offline/locked, passed.

• Docs: 26 Markdown files passed; local anchors are not checked.

• Smoke safety: seven preflight fixtures and cleanup checks passed with fake processes/tasks.

• Release binary --help/--version passed with empty stderr and unchanged SHA256. No state-changing runtime smoke or physical/elevated acceptance was run locally.

• scripts/check.ps1 -Mode Full passes for Rust changes (or -Mode Docs for docs only). Full was not run locally because it includes a real Power Request test; its safe components above passed.

• tests/developer_checks.ps1 if developer tooling changed: not applicable; tooling unchanged.

• tests/smoke_safety.ps1 passes.

• Relevant smoke/manual checks run in an isolated environment, or skips explained above.

• Docs updated if behavior changed: existing contract restored, no contract change.

Checklist

• Base branch stated; main is the requested integration target.
• Existing IPC architecture retained: control/status separation, same-user/elevation checks, request bounds and pipe modes preserved. Existing connected-response waits and control startup cleanup paths remain separate scope.
• Business-model changes: not applicable.