fix(security): update OSS dependencies to remediate 3 high-severity CVEs

[johntmyers]

Summary

Update three OSS dependencies flagged in the April 1, 2026 Security Tracker to their patched versions. All three are lockfile-only changes with no source code modifications.

Changes

tar 0.4.44 -> 0.4.45 (Rust)

• CVE-2026-33055 (High): tar-rs versions <= 0.4.44 have conditional logic that skips the PAX size header when the base header size is nonzero, enabling potential archive manipulation.
• Dep chain: openshell-bootstrap, openshell-cli -> tar

aws-lc-rs 1.16.1 -> 1.16.2 / aws-lc-sys 0.38.0 -> 0.39.1 (Rust)

• BDSA-2026-5232 (High): AWS-LC name constraints bypass due to improper certificate validation, allowing wildcard or raw UTF-8 Unicode certificates to bypass constraints.
• Dep chain: openshell-sandbox, openshell-server -> russh -> aws-lc-rs -> aws-lc-sys

Pygments 2.19.2 -> 2.20.0 (Python)

• BDSA-2026-5113 / CVE-2026-4539 (High): Catastrophic regex backtracking in AdlLexer (lexers/archetype.py), enabling remote DoS via crafted input.
• Dep chain: transitive dev dependency via sphinx / accessible-pygments

Testing

• mise run pre-commit passes
• mise run test passes
• cargo build succeeds (verifies Rust lockfile is valid)
• uv sync succeeds (verifies Python lockfile is valid)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)