feat: add windows sing-box cli

[pixelcola]

Summary

• add Typer-based sing CLI commands for installing and controlling the sing-box Windows service
• add local profile state management, profile downloads, and sc.exe service wrappers
• add pytest coverage plus CI/docs/spec updates for the new command contract

Tests

• uv run ruff format --check --diff src tests
• uv run ruff check src tests
• uv run ty check src
• uv run pytest