Add /smart-router status with a native ON/OFF badge

[lilly-luo]

/smart-router status now reports whether routing is on or off in the current session. Claude renders ⚡ Unity Gateway Smart Router beside a green ON or gray OFF badge with its native TypeScript Box and Text components, following the visual pattern in #977. Codex and Claude sessions without mods use a text fallback.

The read-only --smart-routing-status CLI flag resolves the agent's routing preset and latest session overrides. Invalid controls report an error, and status cannot be combined with a toggle. Reading status does not launch an agent or change routing or orchestration.

Validation:

• 884 focused Python tests passed across CLI, routing/configuration, skills, and integration contracts.
• All 21 Smart Router component tests passed after extending the installed-skill subprocess checks for status.
• Three native Claude 2.1.296 checks passed, including plugin validation, terminal/desktop badge trees, and status reads without inference.
• Repository Ruff lint/format, type checks, and diff checks passed.

Live interactive painting and PowerShell execution were not checked; native checks used Claude 2.1.296.