The Routing-mode toggle had Anthropic / Ollama / Self-Hosted / Mix but no way
to route the whole org to Grok. Add it end to end:
- backend: apply_mode("grok") + _apply_grok (GLOBAL default -> grok-build-0.1) +
derive_mode "grok" detection; ApplyModeRequest/ModeResponse accept "grok".
- panel: a "Grok" routing-mode card (between Anthropic and Ollama, gated on the
xAI key) + flipToGrok; a Grok group in the per-agent mix dropdown +
catalogGrokOnly + a grok ProviderBadge variant; the mix-save key check and
the AI-routing description now cover Grok.
- tests: integration derive_mode/apply_mode "grok" cases (+ grok provider row
in the fixture).
Gated: ruff + mypy clean; panel typecheck + lint clean.