fix(windows): repair install.ps1, honest dry-run status, deterministic daemon_ipc - #1320

…atus

The Windows smoke guards that an invalid PATH seam must fail closed rather than
silently falling back to the live HKCU\Environment\Path. That guard went green
in a way that meant nothing: the seam still refused, and install still printed
"PATH configuration failed", but the process exited 0.

Windows release builds used to compile a separate managed-install path. With one
binary per platform they compile the shared cbm_cmd_install, which since 30b5f12
downgraded ANY failed dry-run plan check to CLI_OK. That commit was fixing a real
complaint -- the dry-run summary was being skipped entirely on Windows -- but it
bundled the exit status into the fix. Keeping the summary is right; reporting
success is not. --dry-run exists to answer "would this install work?", so a
caller that only sees the exit code could not tell a refused PATH probe from a
clean plan.

The summary and the triage note still print; only the status changes. A real
install already failed non-zero here, so the fail-closed behaviour itself was
never at risk -- just its observability.

The smoke also still encoded the launcher-era portable-vs-managed split, which
does not survive one-binary-per-platform:

  * 6b expected uninstall to be REFUSED. That refusal existed because a portable
    extracted bundle was a different artifact from the launcher-managed install
    it would have torn down. The extracted binary now IS the installed one.
  * 6c expected update to be REFUSED, contradicting the contract Phase 14a
    asserts against a real update: Windows hands off to install.ps1, exits 0 and
    prints the command. 6c now pins that same handoff.
  * 14a compared binaries with cmp, which is absent from the Windows MSYS shell,
    so it reported "different" for two copies of one file. Hashes instead, the
    way Phase 12 already verifies the release archive.
  * 14f seeded the MCP entry at the RETIRED binary. The old launcher-managed
    update rewrote that entry in-process; the handoff does not, so uninstall
    correctly declined to remove an entry owned by a different installation and
    the phase demanded the one thing it must never do. It now seeds the
    installed binary, which is what install.ps1 leaves a real user holding.

Signed-off-by: Martin Vogel <[email protected]>

…ling for it

Two Windows tests needed the startup thread to be observed HOLDING the startup
lock, and looked for it by polling the lock for BUSY up to 200 times. That state
has no lower bound: whenever the rendezvous handoff does not block, acquire ->
handoff -> release completes in microseconds, so the window can close between
two polls and startup_observed asserts on a coin flip. This blocked release run
30374135923 on test-windows (windows-2025, CLANG64, x86_64).

Budget-tuning the poll was tried and rejected -- a wider budget only lowers the
failure rate, and a transient window is never a fixed test. Instead the
production path exposes a gate that fires once the startup lock is held and
before the handoff runs, matching the hook pattern already used for POSIX
publication. The test parks the startup thread there and releases it when it is
ready, so the interleaving is pinned by construction. The acquired flag is
monotonic, so the observation cannot be missed; the remaining bound only catches
a thread that never started at all. The gate is inert unless a test installs it.

Also fixes an unrelated use-after-free this exposed. ipc_forever_wait_server
closed the connection and NULLed it from the server thread, while the test was
about to call cbm_daemon_ipc_connection_interrupt on the pointer it had already
loaded -- and receive_frame can return on its own before that call lands. It
crashed roughly one Windows run in five, independent of the change above.
Ownership now stays with the test, which closes after joining, so interrupt can
only ever see a live connection.

Verified on real Windows: 5 consecutive daemon_ipc runs, no failure and no
crash. macOS 46 passed x5 under ASan/UBSan; Linux 6606 passed, 0 failed.

Signed-off-by: Martin Vogel <[email protected]>