fix: repair hoisted node-pty helper permissions on install

[James3014]

Owner scope amendment — macOS only (2026-09-11)

依 Owner 最新裁決，本工作線相關功能設計、實作、交付與驗收 只處理 macOS。本裁決取代下文較早的跨平台／三平台要求。

• Windows、Linux 支援、移植、修復與平台驗證不在本次工作範圍；不再以三平台全綠作為本工作線的 acceptance criterion。
• 驗收保留 macOS 上必要的 source tests、獨立 package/install、真實呼叫入口、operation／副作用／讀回及適用的恢復與終態證據；ownership、lease、CAS、安全與獨立審查要求保持有效。
• 下方歷史測試、PR、平台結果與問題紀錄保留作為歷史證據，不代表目前仍有跨平台交付承諾。後續設計及驗收計畫以此 macOS-only 範圍為準。
• 本次更新僅修正 Issue 與規劃範圍；實作、部署與重啟仍依 Owner 的暫停指令保持暫停。
• 此文字更新不會自行修改 GitHub CI 設定或 branch protection；既有檢查設定如與新範圍不符，須另行明確調整，不得假稱已通過或繞過保護。

Agent 執行指令：停止 Windows／Linux 專屬實作、修復及三平台驗收工作；後續工作只以 macOS 為目標。

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Fixes #76.

Fresh prefix installs hoist node-pty outside DevSpace's own node_modules, leaving Darwin spawn-helper files non-executable. Resolve node-pty/package.json relative to the postinstall hook and repair only its two Darwin helpers. Missing optional node-pty and non-Darwin hosts remain no-ops; unrelated resolver failures propagate.

At candidate 25553bf, six focused tests, typecheck, build and diff checks passed. A fresh npm pack and independent-prefix installation, without manual chmod, produced 0755 helpers and a real node-pty /bin/echo canary with expected output and exit 0. Independent exact-head source review accepted this revision. The regression tests are included in npm test for the existing three-platform CI. No deployment is included.

[James3014]

Superseded by rebind codex/issue-76-hoisted-pty-permissions-final onto fresh main d84d66c.