Add experimental KeySilk portable keypad adapter

[ZephyrKeXiner]

Summary

• add a portable-keypad SDK with a keysilk_v1 adapter prototype
• add a KeySilk plugin wrapper and companion-profile runtime
• add macOS host actions for URL/path opening, text paste, and global hotkeys
• add integration notes, captured derived samples, and a manual smoke-test plan

Why this remains a draft

This work cannot currently be treated as a supported hardware adapter:

• no KeySilk device is available to the current maintainer for reproduction
• no vendor protocol documentation or reproducible packet captures are included
• direct device I/O depends on an uncommitted sdks/tools/bin/KeySilkHidTool.exe
• the desktop host does not expose the required generic HID list/read/write APIs
• the included shortcut demo can be triggered from any keyboard and does not validate KeySilk hardware
• companion profiles are not persisted across application restarts
• several capabilities are labeled hardware-verified without repository-contained evidence

Required before review

• provide the exact device model, firmware version, and test hardware
• include protocol provenance, packet captures, and original before/after config binaries
• provide source and build instructions for the HID transport, or replace it with a native host transport
• add backup, restore, write verification, and unknown-firmware safety behavior
• add reproducible codec fixtures and physical-device end-to-end tests
• integrate the device through the generic keyboard adapter architecture rather than KeySilk-specific host RPCs

Checks completed on the isolated commit

• Node syntax checks passed
• SDK package dry run passed (17 files)
• TypeScript SDK tests passed (2/2)
• TypeScript SDK and KeySilk plugin builds passed
• macOS PluginShowcase Swift target built successfully
• simulated JSON-RPC companion chain passed: register hotkey → trigger → open URL → unregister

These checks validate the software scaffold only; they do not validate device communication or physical hardware behavior.