[codex] Grant Windows sandbox access to primary runtime

[abhinav-oai]

Why

Codex Desktop installs its managed primary runtime under %USERPROFILE%\.cache\codex-runtimes. Elevated Windows sandbox commands run as dedicated sandbox users. The synchronous runtime ACL refresh repairs read/execute access for the Desktop runtime directories under %LOCALAPPDATA%\OpenAI\Codex, but did not include the managed primary runtime cache.

As a result, the Desktop app could discover a bundled runtime while a sandboxed command received ACCESS_DENIED when reading or executing it.

What changed

• Include %USERPROFILE%\.cache\codex-runtimes in the managed runtime paths considered by the Windows sandbox ACL refresh.
• Reuse the existing inherited read/execute ACL repair; no write permission is added.
• Add Windows-target regression coverage for the runtime path list and the primary-runtime-only case.

Impact

Bundled Python, Node, and native tools remain usable from elevated Windows sandbox sessions without broadening write access or granting access to the rest of the user profile.

Validation

• just fmt
• just test -p codex-windows-sandbox (10/10 host-side tests passed)
• Windows-target path tests included for CI