fix(build): use zig archive tools for cross builds

[TaylorMutch]

Summary

Fix local cross-compilation of bundled Z3 by configuring the Zig CMake toolchain with Zig-backed ar and ranlib wrappers. This prevents macOS /usr/bin/ar/ranlib from producing invalid archives for Linux targets during local Helm/Skaffold image builds.

Related Issue

N/A

Changes

• Generate ar and ranlib wrappers next to the existing Zig cc/c++ wrappers.
• Set CMAKE_AR and CMAKE_RANLIB in the generated CMake toolchain file.
• Export target-specific AR_* and RANLIB_* variables for build scripts that honor them.

Testing

• tasks/scripts/setup-zig-cc-wrapper.sh aarch64-unknown-linux-gnu.2.28 aarch64-unknown-linux-gnu.2.28 /private/tmp/openshell-zig-wrapper-pr-check
• mise run pre-commit passes

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)

[maxamillion]

LGTM