test(skills): cover Windows catalog

[orangeCatDeveloper]

Fixes #3901

Summary

Windows could report a healthy Skill Catalog suite while six filesystem, recovery, and multi-client contracts never ran.

Five tests returned before their assertions on Windows, while the real two-client transport test carried an explicit Windows skip. The tests now use Windows ACLs for unreadable fixtures, accept the Windows process-termination representation, exercise the existing named-pipe transport with an isolated skill home, and retain the open-handle and symlink recovery assertions.

The blocking Windows recovery lane runs every Skill Catalog test file and requires exactly 90 passes with zero skips; its CI contract prevents the file list or count from silently shrinking.

Verification

Before:

447:  if (process.platform === 'win32') return;
466:  if (process.platform === 'win32') return;
216:  if (process.platform === 'win32') return;
540:  if (process.platform === 'win32') return;
625:  if (process.platform === 'win32') return;
44:  skip: process.platform === 'win32',

After (Windows recovery run):

# tests 90
# suites 1
# pass 90
# fail 0
# cancelled 0
# skipped 0
# todo 0

AI use

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex implemented the cross-platform test fixtures and Windows CI gate, then performed local validation and an independent subagent review.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No