Report memory metadata in winml sys JSON

[Yue Sun (KayMKM)]

Summary

• add a versioned schema marker and installed physical memory to the full winml sys --format json payload
• expose dedicated GPU memory in device details when Windows reports it
• document the JSON memory fields and cover best-effort probe behavior with unit and hardware-backed E2E tests

Validation

• uv run --frozen ruff check --fix src/winml/modelkit/commands/sys.py tests/e2e/test_sys_e2e.py tests/unit/commands/test_sys_device_info.py
• uv run --frozen pytest tests/unit/commands/test_sys_device_info.py -q (11 passed)
• uv run --frozen pytest tests/e2e/test_sys_e2e.py -m e2e -q (20 passed)

[Qiong Wu (qiowu) (DingmaomaoBJTU)]

Reviewed the JSON schema additions and memory probes. The new fields are scoped correctly to the full system/device report, but there are two blocking issues: the current head fails required mypy, and the exposed GPU capacity is sourced from a 32-bit WMI field that truncates/caps modern GPU memory. Details inline.