Document macOS setup and development

[fakebob2004]

What changed

• add complete English and Chinese macOS operation guides
• document the exact built-in macOS setting used to ignore the internal trackpad when an external mouse is present
• add bilingual macOS development history covering raw contact feasibility, ABI isolation, 125 Hz five-contact validation, MTP1 transport, sequence/reconnect fixes, Y-axis mapping, and the decision not to intercept local input
• link the new documentation from both repository READMEs and the existing Mac handoff

Why

The working prototype had detailed Windows documentation but the Mac setup and engineering decisions were scattered across handoff notes. These documents make the current operating procedure and the intentionally small Mac architecture understandable to users and contributors.

Validation

• make test
• markdown local-link validation
• git diff --check