test(smoke): retire the Windows Phase 14 missing-executable requirement

[DeusData]

Release run 30384603265 failed all 30 test jobs -- Windows, macOS and Linux
alike -- from a single stale contract requirement. test_smoke_fixture_contract.sh
runs as step zero of every test leg, so one violation reddens the whole matrix.

The contract pinned a literal string so Windows Phase 14 would carry an MCP entry
naming a missing executable. Because it matched only the STRING and never the
property, it kept passing after the property was gone -- twice over:

• the fixture now copies a binary to the retired path (added with the
  launcher removal), so that path stopped being missing regardless of the string
• Windows update is a handoff to install.ps1, so nothing rewrites the entry
  in-process the way the launcher-managed update did

An entry naming a foreign path therefore survives to uninstall, which correctly
refuses to remove a config entry owned by a different installation -- making
Phase 14f assert precisely the removal uninstall must never perform.

The requirement now pins the installed binary, which is what install.ps1
leaves a real Windows user holding.

No coverage is dropped. The missing-executable classification moves to named
unit tests rather than this fixture:
cli_editor_mcp_preserves_unrecorded_posix_absolute_entries_without_probe and
cli_editor_mcp_preserves_unsafe_windows_drive_probe (the latter covering the
Windows missing-drive case specifically).

Verification

All 10 shell contract tests scripts/test.sh runs pass locally:

test_build_dir_safety                 PASS   test_soak_daemon_recovery_contract  PASS
test_makefile_ts_runtime_dependencies PASS   test_ui_dev_proxy_security          PASS
test_parallel_harness_contract        PASS   test_venue_parity_contract          PASS
test_security_strings_allowlist       PASS   test_vm_worktree_manifest           PASS
test_smoke_fixture_contract           PASS   test_windows_bundle_contract        PASS

Root cause confirmed identical on a macOS job and a Linux job from the failed
run, not inferred from the Linux one alone.