fix(workflow): expose macOS hdc toolchain

[Mydstiny]

Summary:

• Add the DevEco and standalone API 23 SDK toolchains directories to the macOS environment PATH, with the full HarmonyOS SDK preferred.
• Record the hdc diagnosis and sanitized cross-device handoff state.

Verification:

• Opus and RustDesk FFI builds passed for arm64-v8a and x86_64.
• assembleHap --no-daemon passed through SignHap with the local signing profile.
• Light open-source compliance, finish-check, shell syntax, and diff checks passed.
• hdc 3.2.0d starts successfully; list targets is [Empty] because no device is connected or authorized.

No runtime code was changed. Please merge with a merge commit after open-source-compliance passes.