Add macOS arm64 developer support

[huangminghuang]

Summary

Adds macOS Apple Silicon support for Wire Sysio, including the Release CI path, Apple arm64 dependency registry updates, macOS-safe CMake/runtime gates, and native-debug host integration.

What changed

• Adds a macos-15 Apple Silicon workflow that configures a Release build, builds all, and runs the parallelizable CTest set.
• Adds an arm64-osx-release vcpkg overlay triplet matching the Linux release-triplet pattern, including release-only vcpkg dependencies and ccache launchers.
• Pins the Wire vcpkg registry updates for macOS-compatible Boost, SoftFloat, secp256k1, and wire-sys-vm ports.
• Gates Linux/x86-only behavior away from macOS, including linker flags, LLVM/JIT/OC assumptions, sys-vm runtime selection, and allocator defaults.
• Defaults jemalloc off on macOS while preserving Linux defaults and sanitizer auto-disable behavior.
• Updates SoftFloat type handling and related serialization/precondition paths for Apple arm64 compatibility.
• Fixes AppleClang build issues in test/example code, including large integer literal typing, std::chrono::utc_clock, and unsupported std::format usage.
• Skips sys-vm-oc-only chain plugin tests when OC is not enabled.
• Enables macOS Debug native-module host support by allowing native-module on Apple Debug builds and generating Apple -exported_symbols_list files for native intrinsic exports.
• Documents macOS developer setup and native-debug behavior in README.md, AGENTS.md, CLAUDE.md, and contracts/native-debug.md.

Why

The repo could not reliably configure, build, or test on Apple Silicon because Linux linker flags, allocator assumptions, x86-only runtime assumptions, GNU/libstdc++ expectations, and pre-merged vcpkg registry gaps leaked into the macOS path.

This PR narrows the supported macOS path to an Apple Silicon Release CI build using checked-in contract artifacts and interpreted sys-vm, while also preparing Debug-only native contract debugging now that CDT can emit Mach-O _native.so modules.

Testing

• Configured macOS arm64 Release builds with arm64-osx and arm64-osx-release triplet settings.
• Built local macOS arm64 Release all target successfully before switching CI to Release mode.
• Ran macOS arm64 parallelizable CTest locally after the Release build; remaining prior CI issue was diagnosed as Debug-mode runtime/timeout pressure, so CI now uses Release.
• Ran five nonparallelizable tests locally on macOS arm64: http_plugin_unit_tests, nodeop_sanity_test, block_log_util_test, kiod_auto_launch_test, and cli_test.
• Ran nodeop_run_test locally on macOS arm64 successfully.
• Configured macOS native-debug build against local CDT with native-module enabled.
• Built native_export_list, native_intrinsic_exports, unit_test, contracts_unit_test, and sysio.token_native.
• Verified sysio.token_native.so is a Mach-O arm64 bundle exporting _apply.
• Verified macOS host executables export native intrinsic symbols such as _require_auth and _prints.
• Ran native_overlay_tests -- --native-module: 3/3 passed.
• Ran contracts_unit_test --run_test=sysio_token_tests -- --native-module: 10/10 passed, 138 assertions.
• Validated workflow YAML after edits.

Related PRs

• Add macOS arm64 native support wire-cdt#66 adds the CDT-side native contract compilation support needed to emit macOS Mach-O _native.so modules. This sysio PR consumes that capability for local Debug native-module loading and host intrinsic export support.

Notes

• macOS CI intentionally uses Release mode and interpreted sys-vm only. It does not build contracts through CDT and does not run native-module tests.
• Local macOS Debug native contract debugging is in scope for this PR when paired with Add macOS arm64 native support wire-cdt#66: sysio enables native-module, exports host intrinsics with the macOS linker format, and documents the LLDB/native-module workflow.
• sys-vm-jit, sys-vm-oc, CDT contract rebuilds in CI, and native-debug CI coverage remain out of scope for this PR.