fix(windows): skip nested junctions in Glob roots

[liubf21]

Summary

Fixes #3938

Allow recursive Glob roots to contain a validated nested NTFS junction. The broker skips the junction instead of traversing it, so ordinary files remain enumerable while the junction target receives no AppContainer ACE. Reparse-point roots, symlinks, volume mounts, file reparse points, and unsupported tags remain fail-closed.

Verification

• cargo fmt --check
• cargo check --locked --tests --target x86_64-pc-windows-gnu
• npm exec biome lint packages/runtime/src/__tests__/filesystem-worker-windows-smoke.test.ts packages/runtime/src/filesystem-worker/sandbox-paths.ts
• npm --workspace @maka/runtime run build
• Focused filesystem-worker tests: 52 passed
• git diff --check
• Native Windows junction/ACL execution is pending Windows CI; the local Windows smoke suite is skipped on macOS.

Security

The nested exception is deliberately narrow: the broker reads reparse data, admits only directory mount-point tags whose substitute target is a local drive path, and continues rejecting all other reparse forms.

AI use

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

Tool(s) and scope: Codex assisted investigation, implementation, tests, documentation, and review. Commit f7f28c971099c852fa7f4ee8240fb21c11d925b2 carries Generated-by: Codex.

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