refactor(plugin): add Python-free Windows OS primitives

[kmbroai]

Summary

Add the Windows OS primitives needed for TypeScript to replace the Python filesystem and locking helpers.

Changes

• Use Rust File to own Windows handles and provide ordinary I/O, cursor-preserving truncation, flush, and exclusive whole-file locks. Keep Win32 metadata, identity, paths, and exact-handle rename/deletion. Preserve raw UTF-16 paths and numeric Windows errors, including closed-handle error 6 and contention error 33.
• Split the native crate into Unix and Windows modules, retaining the existing Unix implementation.
• Add x64 and arm64 Windows artifact jobs with Node 20.0 and 22.13 proofs for directory sharing, junctions, handle lifetime, and cross-process locks.

Testing

• Both x64 and arm64 MSVC-target Clippy checks, Rust formatting, CI-tool compilation, proof syntax, Prettier, actionlint, Ruff, portable source checks, and all nine checker tests passed locally.
• Windows proofs cover I/O errors, cursor/EOF behavior, handle lifetime, whole-file contention, and unlock/close/process-death release. A separate Node 22 invocation compares both directions against the existing Python completion-lock functions.
• Actual x64/arm64 Windows execution on Node 20.0 and 22.13, including the optional Python comparison, remains a hosted CI gate for this head.

Risk and rollout

Stacked on #794. This is opt-in preparation; product commands do not use the new bindings yet. Universal package assembly and successful native Windows proofs are required before the TypeScript callers replace Python.

Public disclosure review

• No customer, partner, prospect, or user identities, data, or identifying details are included.
• No credentials, personal data, private source, scan findings, or nonpublic links or tickets are included.
• I reviewed the branch name, title, description, commits, changes, comments, logs, screenshots, attachments, and links for public disclosure.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
🔒 Security Review	✅ Completed 2026-09-05T01:19:36.048264Z	7eaffc5	New commits

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[mldangelo-oai]

Reviewed 90e2987. The native Windows x64 and arm64 proofs pass, and I found no actionable binding issues.

Holding approval for the Windows package verification timeout. The log reports successful installed-package validation before the outer smoke process hits its 210-second timeout. Please rerun this job on the reviewed head. If it repeats, investigate smoke-process exit and cleanup; the log alone does not establish a native-binding regression.

[mldangelo-oai]

The Windows package verification rerun passed on the unchanged reviewed head, clearing my earlier hold. Both native Windows x64 and arm64 proofs pass. No actionable findings in the binding changes.

[mldangelo-oai]

The exact-head Windows proofs are green; this is a non-blocking simplification follow-up.