CHEF-34743: Add Habitat plan for aarch64-darwin (macOS Apple Silicon)

[sanghinitin]

Summary

Adds a Habitat package plan for aarch64-darwin (macOS Apple Silicon) platform to enable native Habitat builds on Apple Silicon Macs.

Jira Ticket

CHEF-34743

Changes

• Created habitat/aarch64-darwin/plan.sh for macOS aarch64-darwin builds
• Uses core/clang and core/cmake for native macOS compilation (instead of gcc)
• Sets DYLD_LIBRARY_PATH for macOS dynamic linker in the runtime wrapper
• Configures CC/CXX environment variables pointing to clang
• Adds core/libarchive as a runtime dependency
• Includes binstub patch verification to fail fast on injection errors

Evidence / Testing

• Plan structure follows the established pattern from the chef-cli aarch64-darwin plan
• Uses the same base-2025 builder channel as the existing Linux plan
• Path references adjusted for the nested habitat/aarch64-darwin/ directory structure ($PLAN_CONTEXT/../..)
• Verified plan syntax and all required Habitat callbacks are present

[github-actions]

Simplecov Report

Covered	Threshold
98.57%	90%